GCSE physics whole course ammended to P2 2010

Document Sample
GCSE physics whole course ammended to P2 2010 Powered By Docstoc
					AQA GCSE PHYSICS ►
Main Contents ►


                                                                  Use arrow keys to advance within a slide
                                         Cost   Charge
                              Mains                        Control
                                                                     Graphs
                         Energy                                                      Acceleration
                  Voltage                                                                      Friction
                                         Electricity
      Structure                                                              Forces                   Moments

      Types          Radioactivity                                                                    Momentum


    Induction                                           PHYSICS                                            Circular

                                                                                Waves                     Characteristics
Electromagnetism                Energy
                                                                                                    Electromagnetic
              Work                                                                                Optical
                                                          Space                                Sound
                 Resources
                            Efficiency                                               Seismic
                                         Thermal                          Tectonic
                                                       Universe   Solar




              Extras: Electricity, Forces, Waves, Space, Energy, Radioactivity, Links, Terms, Physics

                                  Click on this bar to return to this slide
Electricity ► Idea map




1                Electron
                                      Atom



                                             Proton   Neutron


       Moving               Stationary


       Current               Charge




       Voltage           Energy          Mains        Control


                                             Cost
Electricity ► Voltage ► Idea map




1.1               Energy              Electrons

                                           causes...
                           Voltage                         Current


                                                           Circuit


      Series        Parallel              Components



                  Ammeter          Voltmeter      Thermistor         LDR
Electricity ► Voltage ► Energy and Electrons




 •   Electricity is fundamentally about 2 things…




                   •   Energy                       •   Electrons
                   •   Ability to do                •   Tiny particle
                   •   Invisible                    •   Carry charge
                                                    •   Carry Energy
                                                    •   Effectively Invisible
Electricity ► Voltage ► Current




        •    Electric Current
        •    Current
        •    Flow of charge         Mean the same
        •    Electricity
        •    Moving Electrons
        •    Symbol I




            Small Current         Large Current
Electricity ► Voltage ► Amps




                                              A



•   The current flowing through a component in a circuit is measured in amperes (A).

•   An ammeter is connected in series with the component.

•   1 Amp = 6 billion billion electrons per second
Electricity ► Voltage ► Voltage Idea



        •     Energy per electron
        •     Voltage                        Mean the same
        •     Potential Energy
        •     Potential
        •     Symbol V




            Low Voltage                High Voltage



                Low energy Electron          High energy Electron
Electricity ► Voltage ► Potential Difference




                                           •   Potential Energy Difference
                          Mean the same        between 2 points on a wire
                                           •   Potential Difference
                                           •   P.D.
                                           •   Difference in Voltage
                                           •
                 Energy



                                               Voltage across
Electricity ► Voltage ► Voltmeter




                                 V
                               4 Volts



     The p.d. across a component in a circuit is measured in volts (V)

     A voltmeter connected across (in parallel with) the component.
Electricity ► Voltage ► Relationship Concept




   • The next four slides make essentially the same point about the
     relationship between current and voltage…



   •   Relationship
   •   Proportional
   •   Connection
   •   One can be worked out from the other
                                                              Mean the same
   •   One causes a change in the other
   •   Link
   •   A formula allows us to calculate a value
   •   Dependent
Electricity ► Voltage ► Voltage needed




   • A current will flow through an electrical component (or device)…

   • Only if there is a voltage or potential difference (p.d.) across its ends.
Electricity ► Voltage ► More voltage, more current




• The bigger the potential difference across a component…

• The bigger the current that flows through it.
Electricity ► Voltage ► Graphing Relationship




             Current



                                                   Proportional : As one value increases
                                                   so does a second value




                                 Voltage



    •   Current-voltage graphs are used to show how the…

    •   Current through a component varies with the voltage across it.
Electricity ► Voltage ► V = I R




      • The current through a resistor (at constant temperature) is
        proportional to the voltage across the resistor.

          Voltage      =     Current        x          Resistance
             V         =          I         x              R
          10 Volts     =     2 Amps         x           5 Ohms
Electricity ► Voltage ► Series Circuit


                   3A      12 V


                                      3A
                                                              3A
                              6V            6V
                               2Ω           2Ω

                                      4Ω



    •   When components are connected in series:

    •   Their total resistance is the sum of their separate resistances.
    •   The same current flows through each component.
    •   The total potential difference of the supply is shared between them
Electricity ► Voltage ► Parallel Circuit



                            12 V
           3A

                                                               3A
                               12 V          2A



                                      12 V



                                                    1A
 •   When components are connected in parallel:

 •   The current in the branches equals that leaving the battery
 •   The current may vary from branch to branch
 •   The total potential difference of the supply is same for each branch
Electricity ► Voltage ► Filament Bulb

     Resistance




                      Temperature




    • The resistance of a filament lamp increases…
    • As the temperature of the filament increases.
Electricity ► Voltage ► Diode




                                                CURRENT
                                                                       normal flow


                                                          VOLTAGE


                                          no flow




    • The current through a diode flows in one direction only.

    • The diode has a very high resistance in the reverse direction.
Electricity ► Voltage ► Light Dependent Resistor




                    1000 Ω                          10 Ω




    •   Could be called “darkness dependent resistor”
    •   The resistance of a light dependent resistor decreases…
    •   As the light intensity increases.
    •   It resists when it is dark…
Electricity ► Voltage ► Thermistor




                  1000 Ω                    10 Ω




          •   A “coldness dependent resistor”
          •   The resistance of a thermistor decreases…
          •   As the temperature increases.
          •   Resists when it is cold
Electricity ► Voltage ► Symbols




                         Cell     Switch (open)
    Battery                                           Switch (closed)




 Variable resistor                                           L.D.R



   Fuse                                                       Diode

                                                  A

                     Resistor
                                        V              Ammeter
                                                      Lamp
                     Thermistor
                                  Voltmeter
Electricity ► Energy ► Ideas map




1.2                 deliver…
                               Electrons

                                              in a certain…
                                                               Coulomb


                               Energy (J)         Time (s)


                    to give us…
                                Power                        Watt (J per s)




                     Voltage       x    Current
Electricity ► Energy ► Electrons carries energy




                     10 J                                 £20




                 •   This is an electron
                 •   It collects energy at the battery…
                 •   Travels around a circuit…
                 •   And delivers it to a component
Electricity ► Energy ► Electrons deliver Energy



          30 J                                          £30


                                                       Bank



                                                       Shop         Shop

           20 J          10 J                          £20          £10



   • As an electric current flows through a circuit, energy is transferred

   • The energy is transferred from the battery or power supply…

   •   …to the components in the electrical circuit.
Electricity ► Energy ► Heat from a wire




    •   When Charge flows through a resistor, electrical energy is
        transferred as heat.
Electricity ► Energy ► Energy per Time
Electricity ► Energy ► Power




   • Power is energy transferred per second
   • Power is measured in Joules per Second known as a Watt
                                                                    10 J
                                                                    10 J
   • 1 Watt = 1 J of energy in 1s




           Power      =    Current     x     Potential Difference
             P        =       I        x              V
          10 Watts    =     2 Amp      x            5 Volt
Electricity ► Energy ► Coulomb




    • Seconds are inconveniently small to measure the age of a person.
    • We use a word which means 31,536,000 seconds.
    • The word is year.


    • Electrons are inconveniently small to measure everyday numbers of electrons.
    • We use a word which means 6,000,000,000,000,000,000 electrons
    • The word is Coulomb.


               1km                   1km


                         1km                   1km


                     1km                    1km

           2 cubic kilometres contain about 6 billion billion grains of salt
Electricity ► Energy ► E = VQ




    • The higher the voltage of a supply…
    • the greater the amount of energy transferred for…
    • a given amount of charge which flows.


          Energy        =   Potential Difference   x       Charge
             E          =            V             x          Q
         10 Joules      =         5 Volts          x      2 Coulombs
Electricity ► Energy ► Q = I t



      3 Coulombs / Sec             …For 5 Seconds…
          (3 Amps)




                                                     Equals 15 Coulombs




             Charge      =       Current      x          Time
                Q        =         I          x            t
          15 Coulombs    =       3 Amps       x       5 seconds
Electricity ► Energy ► Table of 7 key ideas



       DESCRIPTION         NAME         SYMBOL   UNIT

       Ability to do       Energy       E        Joule (J)

       Electrons           Charge       Q        Coulomb (C)

       Change              Time         t        Second (s)


       Charge per Time     Current      I        Amp (A)

       Energy per Charge   Voltage      V        Volt (V)

       Energy per Time     Power        P        Watt (W)


       Obstacle            Resistance   R        Ohm (Ώ)
Electricity ► Energy ► 7 ideas connected




                      R

                                           1.V=IR
               V            I
                                           2. E = V Q

                                           3. E = P t
          E           Q          t

                                           4. Q = I T

                                           5. P = I V
                      P
Electricity ► Mains ► Ideas map




1.3              Direct
                        Types of Current

                                       Alternating

                                           Mains


                Plug                                  Safety



     Live     Neutral        Earth             Fuse        Circuit Breaker
Electricity ► Mains ► Mains voltage




              • The UK mains supply is about 230 volts.

              • Mains can kill if it is not used safely.
Electricity ► Mains ► Plug



                                                           Earth pin
         Copper Core




  Plastic Layer                                                                Fuse



                                                                    Live pin

     Plastic Case


                    Neutral Pin                                Cable grip


• Brass Pins and Copper Wires are conductors, plastic is an insulator
Electricity ► Mains ► Alternating Current




    • An alternating current (a.c.) is one which is constantly changing
      direction.

    • Mains is an a.c. supply.

    • In the UK it has a frequency of 50 cycles per second or 50 hertz
      (Hz) which means that it changes direction and back again 50
      times each second.
Electricity ► Mains ► Direct Current




     • Cells and batteries supply a current which always flows
       in the same direction.

     • This is called a direct current (d.c.).
Electricity ► Mains ► Oscilloscope Trace




 a.c.                                 d.c.




        •   Candidates should be able to compare the voltages of d.c.
            supplies…

        •   And the frequencies and peak voltages of a.c. supplies from
            diagrams of oscilloscope traces.
Electricity ► Mains ► Safety




   • If a fault in an electrical circuit or an appliance causes too great
     a current to flow, the circuit is switched off by a

   • fuse
   • or a circuit breaker.
Electricity ► Mains ► Fuse



     Normal                                            Fault


  12 A                                     14 A




      Fuse : 13 A                               Fuse : 13 A



         • When the current through a fuse wire exceeds the current rating
           of the fuse..

         • The wire becomes hot and will (eventually) melt breaking the
           circuit and switching off the current.
Electricity ► Mains ► Fuse selection



                             13                      The Goldilocks and the Three
            Melts too late
                                                     Bears Theory of Fuse Selection™

                             10




                Just right   5

           Melts too soon    3
                             2


                                  Safe   Dangerous


   • The fuse should have a value higher than, but as close as possible
     to, the current through the appliance when it is working normally.

   • The manufacturer will normally recommend a fuse.
Electricity ► Mains ► Circuit Breaker



        Normal                             Fault

          Weak Magnetic Force                   Strong Magnetic Force

   Safe Current                          High Current




    •    A circuit breaker uses an electromagnet to detect a surge and
         operate a very quick automatic off switch.

    •    When the fault is fixed the circuit breaker can be reset.
Electricity ► Mains ► Earth Wire


     No Earth Wire                        Earth Wire




                              Exposed Wire




    • Appliances with metal cases need to be earthed.
    • The earth pin is connected to the case via the yellow/green wire.
    • If a fault in the appliance connects the case to the live wire, and the
      supply is switched on, a very large current flows to earth and
      overloads the fuse.
Electricity ► Mains ► Live Wire




  • The live terminal of the mains
    supply alternates between a
    positive and negative voltage
    with respect to the neutral
    terminal.

  • The neutral terminal stays at a
    voltage close to zero with
    respect to earth.
Electricity ► Charge ► Idea Map




1.5             Extra Electrons
                                  Electrons & Protons



                                        Equal           Lack of Electrons


                    Negative            Neutral             Positive


                     Force                                    Force
                                      Attraction


                                         Uses


                    Photocopier      Electrolysis          Printer
Electricity ► Charge ► Balance of Protons and Electrons




     Electrons
                       -
     Protons           -
                     + -           + -             +
                     + -           + -             +
                     + -           + -             + -

           Extra Electrons        Equal        Lack of Electrons


                 Negative        Neutral            Positive
Electricity ► Charge ► Multiple Terms



   •   Charge
   •   Property of Electrons and Protons           Mean the same
   •   Particles which can exert a force
   •   Ability to create movement

   •   Stationary Electrons
   •   Electrostatics
   •   Static Electricity
   •   Static                                      Mean the same
   •   Trillions of Electrons ‘flooding in’
   •   Trillions of Electrons leaving an area
   •   The balance between Electrons and Protons



   •   Negatively Charged: Extra Electrons         Both Electrically Charged
   •   Positively Charged: Electrons missing
Electricity ► Charge ► Phenomena




    •   When certain different insulating materials are rubbed against each
        other they become electrically charged.

    •   Electrically charged objects attract small objects placed near to
        them.
Electricity ► Charge ► Charges cause Repulsion and
Attraction


             -
             -
           + -                                       +
           + -                                       + -
                                -     -
                                -     -
                              + -     - +
                              + -     - +

    •   When two electrically charged objects are brought close together,
        they exert a force on each other.
    •   These observations can be explained in terms of two types of charge
        called positive (+) and negative (-).
    •   Two objects which have the same type of charge repel.
    •   Two objects which have different types of charge attract.
Electricity ► Charge ► Charge is conserved


               Positive
               Neutral                             Negative
                                                  Neutral


        - +- - ++ - -                       - +- - ++ - -
                 +     +                             +     +
               -
          - + + + + ++                             -
                                              - + + + + ++
         - - - - + - -                       - - - - + - -
        +           +                       +           +
          + + -- + - - -
        - + -                                 + + -- + - - -
                                            - + -
                  +     +                             +     +


    •   When two different materials are rubbed against each other,
        electrons, which have a negative charge, are rubbed off one material
        on to the other.

    •   The material which gains electrons becomes negatively charged. the
        material which loses electrons is left with an equal positive charge.
Electricity ► Charge ► Discharge




    •   A charged conductor can be discharged by connecting it to earth
        with a conductor.
Electricity ► Charge ► Sparks




    •   The greater the charge on an isolated object, the greater the voltage
        (potential difference) between the object and earth.

    •   If the voltage becomes high enough, a spark may jump across the
        gap between the object and any earthed conductor which is brought
        near it.
Electricity ► Charge ► Safety




• Refuelling can be
  dangerous because a
  spark could ignite the
  fumes.

• A wire is used to conduct
  the electrostatic charge
  away safely (discharging).
Electricity ► Charge ► Metal




    •   Metals are good conductors of electricity because some of the
        electrons from their atoms can move freely throughout the metal
        structure.
    Electricity ► Charge ► Photocopier


•    Copying plate is electrically charged.
•    An image of the page you want to copy is projected on to the plate.
•    Where light falls on the plate, the Charge leaks away.
•    The parts of the plate that are still charged attract bits of black powder.
•    The black powder is transferred from the plate to a sheet of paper.
•    The paper is heated to make the black powder stick.
•    There is now a copy of the original page.




                   A
    Electricity ► Charge ► Electrolysis


•     In solid conductors, an electric current is a
      flow of electrons.

•     When some chemical compounds are
      melted or dissolved in water they conduct
      electricity.

•     These compounds are made up of
      electrically charged particles called ions.

•     The current is due to negatively charged
      ions moving to the positive terminal
      (electrode) and the positively charged ions
      moving to the negative electrode.

•     Simpler substances are released at the
      terminals (electrodes). This process is
      called electrolysis.
Electricity ► Charge ► Electrolysis Deposition




         1 amp 1 min               2 amps 1 min              2 amps 2 min


    •   During electrolysis the mass and/or volume of the substance
        deposited or released at the electrode increases in proportion to:

    •   The current.
    •   The time for which the current flows.
Electricity ► Control ► Ideas Map




1.6
                        Sensor                      Capacitor

                                                 Variable Resistor
                                     Modifiers
                                                 Potential Divider



                                                      Relay
                                     Switches
                                                    Transistor

   Logic Gates         Processor                    Time Delay

  AND, OR, NOT
                     Output device
Electricity ► Control ► Electronic Systems




  • Electronic systems have:

  • Input sensors which detect changes in the environment.
  • A processor which decides what action is needed.
  • An output device creates a signal or action.
Electricity ► Control ► Input Sensors




 • Input sensors include:

 • Thermistors which detect changes in temperature
 • LDRs which detect changes in light
 • Switches which respond to pressure, tilt, magnetic fields or moisture.
Electricity ► Control ► Output Devices




                                                 M



 • Output devices include:

 •   Lamps and LEDs (light emitting diode) which produce light
 •   Buzzers which produce sound
 •   Motors which produce movement
 •   Heaters which produce heat
Electricity ► Control ► Variable Resistor




  •   The flow of electricity through a circuit (the current) can be
      controlled by using a fixed or a variable resistor.
Electricity ► Control ► Potential Divider




                       POTENTIAL ENERGY




                V in                      Thermistor      Variable Resistor
                                                       V out


 •   The voltage that is supplied to the potential divider V in ….
 •   is shared across the two resistors.
 •   If either resistance is increased (or reduced), the share of the voltage across it
     also increases (or reduces).
Electricity ► Control ► Equal Resistance




       5000 Ω                                5V

       4000 Ω                                4V

       3000 Ω                                3V

       2000 Ω                                2V

       1000 Ω                                1V

          0Ω                                 0V           Vout



   •   If the two resistors change by the same amount..
   •   They will continue to share the voltage equally
Electricity ► Control ► Unequal Resistance




         5000 Ω                                 5V

         4000 Ω                                 4V

         3000 Ω                                 3V

         2000 Ω                                 2V

         1000 Ω                                 1V

           0Ω                                   0V             Vout



     •    It is the proportion of the resistance that is important.
     •    Here the variable resistor setting affects V out.
Forces ► Idea Map




2
                    Contact
                                  Friction                 Gravity




                                                  Field
                                 Muscular                 Magnetism


                                               Forces



   Balanced                     Unbalanced                 Around Pivot   90o to Motion

No Acceleration                 Acceleration                 Moments        Circular



Constant Velocity             Changing Velocity

    Graphs                       Momentum                     Mass
Forces ► Graphs ► Summary




2.1                                                    Graphs



                           Distance                                     Velocity


                                     Stop                                          Constant Velocity


                                            Velocity (m/s)
  Distance (m)




                 Faster Constant Velocity                        Greater Acceleration



                 Constant Velocity                           Acceleration
                                                                                         Stop

                           Time                                        Time
Forces ► Graphs ► Distance Time

    DISTANCE




               TIME           TIME          TIME




               Distance   =   Speed    x    Time
                  d       =       s    x      t
                24 km     =   6 km/h   x   4 hours
    Forces ► Graphs ► Distance II



•     On a distance-time graph :
•     Stationary objects are
      represented by horizontal                                         Stationary
      lines
•     Objects moving with a




                                     Distance (m)
      steady speed are
      represented by sloping                                            Faster Constant
      straight lines.                                                   Velocity
•     The steeper the slope of the
      graph, the greater the speed
      it represents.
•     If an object moves in a                                    Constant Velocity
      straight line, how far it is                  Stationary
      from a certain point can be                                Time
      represented by a distance-
      time graph.
Forces ► Graphs ► Velocity




                                        Speed: Constant
                                                                    Velocity : Constant
                                        Direction: Constant


 Speed: Constant
                           Velocity : Changing
 Direction: Changing



 •   The velocity of an object is its speed in a given direction.
Forces ► Graphs ► Velocity Time

     VELOCITY




                TIME                   TIME                      TIME




 •   Velocity-time graphs can represent the motion of a body.
 •   The steeper the slope of the graph, the greater the acceleration it represents
 •   Constant velocity it is represented by a horizontal line.
 •   Constant acceleration it is represent by a straight sloping line..
Forces ► Graphs ►Acceleration



           VELOCITY
                                                      Velocity Change


                                        Time

                                       TIME

   • The acceleration of an object is the rate at which its velocity changes.

   • For objects moving in a straight line with a steady acceleration, the
     acceleration, the change in velocity and the time taken for the change are
     related as shown:


          Velocity Change      =     Acceleration     x            Time
                       v-u     =           a          x              t
                      10 m/s   =         2 m/s2       x         5 seconds
Forces ► Graphs ► Gradient for Speed




              DISTANCE


                                                   100 km ÷ 2 hr = 50 km/h




                                         100 km
                               2 hr

                                       TIME




    • Candidates should be able to calculate the gradient / slope of a distance-
      time graph.
Forces ► Graphs ► Gradient for Acceleration




              VELOCITY



                                                    60 m/s ÷ 20 sec = 3 m/s2




                                          60 m/s
                              20 sec

                                        TIME




   • Candidates should be able to calculate:
   • The gradient of a velocity-time graph and interpret this as acceleration.
Forces ► Graphs ► Area for Distance




6 m/s                                  6 m/s




                                          VELOCITY
   VELOCITY




              30m
                                                         15m
                 5 sec                                  5 sec



 • The area under a velocity-time graph. for an object moving with constant
   acceleration represents distance travelled.
Forces ► Acceleration ► Ideas Map




2.2                        Forces                         Newton



                Balanced               Unbalanced

            Constant Velocity          Acceleration                F = ma



            eg 0 m/s or 10 m/s      eg 2 m/s2 or 9 m/s2
Forces ► Acceleration ► Horizontal




           Acceleration   No         Acceleration   Yes
           Speed          ?          Speed          ?
           Direction      ?          Direction      ?
Forces ► Acceleration ► Vertical




           Acceleration   No       Acceleration   Yes
           Speed          ?        Speed          ?
           Direction      ?        Direction      ?
Forces ► Acceleration ► Constant Motion




                                   STOP




              Balanced: 0 km/h                        Balanced: 60 km/h




 • Balanced forces will have no effect on the movement of an object:
 • It will remain stationary or,
 • If it is already moving it will continue to move at the same speed and in the
   same direction.
Forces ► Acceleration ► Balanced Forces




   •   The forces acting on an object may cancel each other out
       (balance).
   •   When an object rests on a surface:
   •   The weight of the object exerts a downward force on the surface
   •   The surface exerts an upwards force on the object
   •   The sizes of the two forces are the same
Forces ► Acceleration ► Unbalanced Forces




    • If the forces acting on an object do not cancel each other out…
    • An unbalanced force will act on the object.
Forces ► Acceleration ► Scenarios



• A stationary object
  will start to move in
  the direction of the
  unbalanced force




• An object moving in
  the direction of the
  force will speed up




• An object moving in
  the opposite direction
  to the force will slow
  down
Forces ► Acceleration ► Size of Resultant Force




                                                            VELOCITY
                                                            VELOCITY
                                                            VELOCITY
 •   The greater the force, the greater the acceleration.
Forces ► Acceleration ► Effect of Mass




 • The bigger the mass of an object…
 • The greater the force needed to give the object a particular acceleration.
Forces ► Acceleration ► Newton


                                     3




                       Speed (m/s)
                                     2

                                     1
          1 kg
                                     0
                                         0        1       2    3
                                                  Time (sec)

       • One newton is the force needed to give a mass of one kilogram an
         acceleration of one metre per second squared.
       • Force, mass and acceleration are related as shown:



             Force                   =       Mass         x    Acceleration
                 F                   =        m           x          a
          100 Newton                 =       2 Kg         x        50 m/s2
Forces ► Acceleration ► Falling Objects




                       4 kg
                                    2 kg
                                           1 kg
Forces ► Acceleration ► Falling Objects II



       Acceleration          =       Force (Weight)         ÷      Mass
                                                   x Gravity (10 N/kg)



           40 N
                      20 N
                                      10 N
 a=               =              =            = 10 m/s2
                                      1 kg
                      2 kg
           4 kg

                             • Therefore, all objects fall at the same
                               speed irrespective of mass
                             • (if we ignore air resistance, Friction)
Forces ► Acceleration ► Effect of Friction


           • Air Friction changes the situation

           • Acceleration = Resultant Force (Weight – Friction) ÷ Mass
           • Friction makes some of the weight effectively unavailable.


              -5N

              40 N         -5N
                           20 N
                                        -5N
                      ≠           ≠
                                        1 kg
                           2 kg
              4 kg
Forces ► Acceleration ► Changing Mass




    Mass    Gravity   Weight   Distance   Friction   Resultant   Acceleration   Time
     kg      N/kg       N         m          N          N           m/s2          s
        1        10       10          2         5            5           5.00    0.89
        2        10       20          2         5           15           7.50    0.73
        3        10       30          2         5           25           8.33    0.69
        4        10       40          2         5           35           8.75    0.68
        5        10       50          2         5           45           9.00    0.67
        6        10       60          2         5           55           9.17    0.66
        7        10       70          2         5           65           9.29    0.66
        8        10       80          2         5           75           9.38    0.65
        9        10       90          2         5           85           9.44    0.65
       10        10      100          2         5           95           9.50    0.65
      Forces ► Acceleration ► Mass vs Descent Time




           0.95

           0.90

           0.85

           0.80
Time (s)




           0.75

           0.70

           0.65

           0.60

           0.55

           0.50
                  0   2         4         6          8   10   12
                                     Mass (Kg)
Forces ► Acceleration ► Effect of Friction


        • If area changes, friction changes (eg Larger Parachute)

        • Acceleration = Resultant Force (Weight – Friction) ÷ Mass
        • Friction makes some of the weight effectively unavailable.


                     -5N         - 10 N       - 15 N

                     40 N         40 N         40 N



                             ≠            ≠

                     4 kg         4 kg         4 kg
Forces ► Acceleration ► Changing Friction




   Mass    Gravity   Weight   Distance   Friction   Resultant   Acceleration   Time
    kg      N/kg       N         m          N          N           m/s2          s
      70        10      700          2       100          600           8.57    0.68
      70        10      700          2       150          550           7.86    0.71
      70        10      700          2       200          500           7.14    0.75
      70        10      700          2       250          450           6.43    0.79
      70        10      700          2       300          400           5.71    0.84
      70        10      700          2       350          350           5.00    0.89
      70        10      700          2       400          300           4.29    0.97
      70        10      700          2       450          250           3.57    1.06
      70        10      700          2       500          200           2.86    1.18
      70        10      700          2       550          150           2.14    1.37
      Forces ► Acceleration ► Friction vs Descent Time


           1.50


           1.40


           1.30


           1.20


           1.10
Time (s)




           1.00


           0.90


           0.80


           0.70


           0.60


           0.50
                  0   100       200         300          400   500   600


                                       Friction (N)
Forces ► Acceleration ► Time Formula



                           acceleration      = velocity change ÷                  time
                                a            =       v-u       ÷                    t
          1.                    v            =         u       +                    at

                         average speed =            distance          ÷           time
          2.               (u + v) ÷ 2    =             s             ÷             t
          1. into 2.     (u + u + at) ÷ 2 =             s             ÷             t

                          u is zero so…
                                ½at     =               s             ÷             t
                                 s      =              ½at2
                               2s ÷ a   =               t2

                                  t          =      √(2s ÷ a)




  s = distance travelled u = initial velocity v = final velocity a = acceleration t = time taken
Forces ► Acceleration ► Equal and Opposite




   •   Whenever two bodies interact…

   •   The forces they exert on each other are equal and opposite.
Forces ► Acceleration ► Unbalanced Forces




 •   If the surface is not strong enough… we have a problem.
Forces ► Friction ► Ideas Map




2.3                                      Friction



                        Fluids                             Solid

                                                          Brakes
                  Air            Water

                                                    Reaction       Braking
                Friction = Weight
                                                         Stopping
                Terminal Velocity
Forces ► Friction ► Types




 • A force of friction acts

 • When an object moves through air or water
 • When solid surfaces slide (or tend to slide) across each other.
Forces ► Friction ► Effects




          friction




   •   The direction of this force of friction is always opposite to the
       direction in which the object or surface is moving.

   •   Friction causes objects to heat up and to wear away at their
       surfaces.

   •   The friction between solid surfaces is used in brakes which slow
       down and stop moving vehicles.
Forces ► Friction ► Braking

     SPEED




                                     TIME


 • The greater the speed of a vehicle:

 • The greater the braking force needed to stop it in a certain distance
 • The greater the distance needed to stop it with a certain braking force
Forces ► Friction ► Skidding




    •   If too great a braking force is applied…

    •   Friction between a vehicle's tyres and the road surface may not be
        great enough to prevent skidding.
    Forces ► Friction ► Stopping Time



                                                                                    reaction time

                                                                                    braking time
          Speed




                                            long stopping distance




                  short stopping distance


                                              Stopping time
•    The overall stopping distance is greater if:                    •   The stopping distance of a
•    The vehicle is initially travelling faster                          vehicle depends on:
•    The driver's reactions are slower (due to                       •   The distance the vehicle travels
     tiredness, drugs, alcohol)                                          during the driver's reaction time.
•    There are adverse weather conditions                            •   The distance the vehicle travels
     (wet/icy roads, poor visibility)                                    under the braking force.
•    The vehicle is poorly maintained (e.g. worn
     brakes/tyres)
Forces ► Friction ► Terminal Velocity




                                  terminal velocity




                                                      deceleration
              acceleration




                                                                                            on ground
                                                                     terminal velocity
                                                                                                        weight

                                                                                                        friction
  force




                                        60 m/s                                      4 m/s
                                                      time

          •             The faster an object moves through a gas or a liquid (a fluid) the greater
          •             the force of friction which acts on it. When a body falls:

          •             Initially it accelerates due to the force of gravity
          •             Frictional forces increase until they balance the gravitational forces
          •             The resultant force eventually reaches zero and the body falls at its
                        terminal velocity
Forces ► Friction ► Terminal Velocity II




                                             Friction




                                           Weight




                 Friction = Weight   therefore there is no acceleration
Forces ► Friction ► Driving




              frictional forces                        driving force




    •   When a vehicle has a steady speed …
    •   The frictional forces balance the driving force.
Forces ► Momentum ► Ideas Map




2.5                        Mass

                              x
                                             Before Collision

                                             After Collision


                                             Before
 Objects have…            Velocity
                                             After
                             =

                      Momentum               Before

                                             After




                 Before              After
Forces ► Momentum ► Impact



 Question: Would you rather be hit with a heavy or a light object?




 Answer: It depends on its speed.
Forces ► Momentum ► Elephant vs Cheetah




    • The greater the mass of an object…
    • and the greater its speed in a particular direction (its velocity)…
    • the more momentum the object has in that direction.

    • Momentum has both magnitude (size) and direction.
Forces ► Momentum ► Calculation




         Momentum, mass and velocity are related as shown:



          Momentum     =         Mass         x       Velocity
          960 kg m/s   =        120 kg        x        8 m/s
Forces ► Momentum ► Collision




   •   When an object collides with another..
   •   The two objects exert a force on each other.
   •   These forces are equal in size but opposite in direction.
   •   Each object experiences a change in momentum which is equal in
       size but opposite in direction.
 Forces ► Momentum ► Collision Calculation




2 Kg x 10 m/s               5 Kg x 6 m/s             2 Kg x 5 m/s         5 Kg x 8 m/s


                50 Kg m/s                                       50 Kg m/s



     •   When a force acts on an object that is moving, or able to move…
     •   A change in momentum occurs.

     •   In any collision/explosion…
     •   the momentum after the collision/explosion is the same as…
     •   the momentum before the collision/explosion. (for a particular direction)
     •   Momentum is conserved when no other/external forces act on the
         colliding/exploding object(s).
Forces ► Momentum ► Collision Calculation II




     •   The force, change in momentum and the time taken for the change
         are related as shown:

     •   Momentum Change (Impulse)       =        Force     x   Time
         10 Kg m/s                       =        1,000 N   x   0.01 s
Forces ► Momentum ► Kinetic Energy




   • When objects collide, the total kinetic energy after the collision in a
     particular direction is normally less than before the collision.

   • Elastic collisions are those involving no overall change in kinetic energy
Energy ► Work ► Ideas Map




5.4                                Energy (J)


                       Useful Energy            Wasted Energy


    Power (J/s)             Work (J)

                       Calculated by                Gravity

                  Movement against force            Elastic

                                                     Inertia

                                                    Friction
Energy ► Work ► Joule
  James Prescott Joule (1818 - 1889)




                                                                        1.0 J

                                                                        0.8 J

                                                                        0.6 J              1 metre

                                                                        0.4 J

                                                                        0.2 J

                                                                        0.0 J   1 Newton




                                  • Energy is measured in joules (J).
  Energy ► Work ► Examples

10,000,000,000,000,000,000,000,000 J                              100,000,000,000,000,000 J




                                                                100 J




 1,000,000,000,000,000 J 10,000,000,000,000 J   100,000,000 J                  1,000 J
Energy ► Work ► Effect of Force




    • When a force moves an object, energy is transferred.

    • Energy transferred is also called work
Energy ► Work ► Calculation




                                                Force




                            Distance



              Energy    =        Force   x   Distance
                 E      =          F     x      d

              9,000 J   =        900 N   x    10 m
Energy ► Work ► Gravitational Potential Energy



    • Gravitational potential energy
      is the energy stored in an
      object

    • Energy is stored because the
      object has been moved against
      the force of gravity.



                 Work                  =   Force    x          Distance
     Gravitational Potential Energy    =   Weight   x    Change in Height
                  GPE                  =     W      x            Δh

                  50 J                 =    10 N    x            5m


                                                        10 N
Energy ► Work ► Mass, Gravity and Weight




          MASS
                                                  GRAVITY FIELD
          WEIGHT
                               MASS

       Force on mass       Amount of matter        Region of influence




              Weight   =        Mass          x    Gravity
                   W   =         m            x       g

               10 N    =        1 kg          x    10 N/kg
 Energy ► Work ► Elastic Potential Energy




• Elastic potential energy is the
  energy stored in an elastic
  object.

• Energy is stored when work is
  done on the object to change
  its shape.




                                    Catapult designed by Leonardo da Vinci
Energy ► Work ► Kinetic Energy



 • Kinetic energy is the energy an
   object has because of its
   movement.

 • An object has more kinetic
   energy:

 • The greater its mass (and
   therefore inertia.

 • The greater its speed


   Kinetic Energy    =           ½ Mass      x   Speed²
         KE          =            ½m         x      v²
        10 J         =          0.5 x 5 kg   x   4 (m/s)2
Energy ► Work ► Power




200,000,000 W                    500,000 W


  • Power (Watts) is a measure of how fast energy is transferred.
  • The greater the power, the more energy is transferred in a given time


           Energy      =        Power         x         Time
                E      =          P           x           t

         5,000,000 J   =    500,000 Watts     x          10 s
Energy ► Work ► Power and Human Activity




        Power (W)            Activity

        800                  playing basketball
        700                  cycling (21 km/h)
        685                  climbing stairs (116 steps/min)
        545                  skating (15 km/h)
        475                  swimming (1.6 km/h)
        440                  playing tennis
        400                  cycling (15 km/h)
        265                  walking (5 km/h)
        210                  sitting with attention focused
        125                  standing at rest
        120                  sitting at rest
        083                  sleeping
Radioactivity ► Ideas Map




 6                                    Atoms



                            Decay                Structure

                      Radioactivity


           Types              Properties      Uses
Radioactivity ► Types ► Ideas Map


                                          Alpha


6.1                           Types        Beta

                                         Gamma

                                       Background
                              Source
      Radioactivity
                                         Specific


     Speed of Decay                    Measuring

        Half Life              Uses    Sterilisation

                                          Tracer
Radioactivity ► Types ► Atoms




                                    •   Every thing is made of atoms




                                •       Iron on Copper The Kanji
                                        characters for "atom."
Radioactivity ► Types ► Stable vs Unstable


 •   There are two kinds of atoms…




            Stable                               Unstable:
                                     Will emit radiation randomly once
    Radioactivity ► Types ► Alpha Beta Gamma


•    Unstable atoms emit 3 types of radiation…



                                                            2 Protons
    ALPHA                                                   2 Neutrons




    BETA                                                    High Energy
                                                            Electron




                                         ALUMINIUM
                                                            High
                            PAPER



    GAMMA




                                                     LEAD
                                                            Frequency
                                                            Wave
Radioactivity ► Types ► Sources


                                                loft insulation




                                                 carpets
   • There are radioactive substances all around us, including in the ground, in
     the air, in building materials and in food.
   • Radiation also reaches us from space.
   • The radiation from all these sources is called background radiation.
Radioactivity ► Types ► Ions




          -1




                       -1                                       -1

        Normal Atom                                      Ion

    •   When radiation from radioactive materials collides with neutral
        atoms or molecules these may become charged (ionised).
    •   When radiation ionises molecules in living cells it can cause
        damage, including cancer.
    •   The larger the dose of radiation the greater the risk of cancer.
Radioactivity ► Types ► Ionising Radiation




 • Higher doses of ionising radiation can kill cells.
 • they are used to kill cancer cells and harmful microorganisms.
Radioactivity ► Types ► Measuring Thickness




   •   As radiation passes through a material it can be absorbed.
   •   The greater the thickness of a material the greater the absorption.
   •   The absorption of radiation can be used to monitor/control the
       thickness of materials.
Radioactivity ► Types ► Interaction with Body




 least        ALPHA
 dangerous
               BETA
 most
 dangerous
              GAMMA


                                                         most
                                                         dangerous


                                                         least
                                                         dangerous




                                                Used as tracer
Radioactivity ► Types ► Monitoring Dosage



         Low Dosage               High Dosage




 • Workers who are at risk from radiation often wear a radiation badge to
   monitor the amount of radiation they have been exposed to over a
   period of time.
 • The badge is a small packet containing photographic film.
 • The more radiation a worker has been exposed to, the darker the film
   is when it has been developed.
Radioactivity ► Types ► Half Life




                                                         100




                                       Undecayed Atoms
                                                         50




                                                          0

                                                               0     14       28
                                                                   Time (s)
 •   The half-life of a radioactive substance:
 •   Is the time it takes for the number of parent atoms in a sample to halve.
 •   Is the time it takes for the count rate from the original substance to fall to
     half its initial level.
Radioactivity ► Structure ► Ideas Map




6.2                             Atomic Structure




           Discovery                Nucleus


         Scattering Exp.           Nucleons

                              Proton         Neutron             Electron



              Type of atom              Isotope        Fission


                Element                 Dating
Radioactivity ► Structure ► Relative Size



    Neutron        Proton        Electron




    • Atoms have a small central nucleus made up of protons and neutrons
      around which there are electrons.

    • To scale above nucleus would be size of a grain of sand.
Radioactivity ► Structure ► Rutherford Expectation


   •    The ‘plum pudding’ model of matter said
        that atoms were solid and uniformly




                                                                                 (1871 - 1937)
                                                                       Lord Ernest Rutherford
        positive with specks of negativity.

   •    If this was the case even a small thickness
        of material should block a stream of alpha
        particles.

   •    Ernest Rutherford decided to test this idea


       What they expected….




                alpha particle source                         alpha detectors
                                                  gold leaf
Radioactivity ► Structure ► Rutherford Result




•    What actually happened….



                                                                           straight
                                                                           through




                                                                  deflection
    reflected back



                     •   Conclusion 1 : The plum pudding model must be wrong
Radioactivity ► Structure ► Rutherford Conclusion


    •   Conclusion 2 : Nuclei are positive and far apart




                      +
                  +




                      +
                  +



                      +
                  +



                                                      simplified gold nucleus
Radioactivity ► Structure ► Masses




                                                                                Electron




                                                             Neutron




•   Kilograms are inconvenient for such tiny masses…
•   So the Atom Mass Unit was invented.
•   Protons and neutrons weigh 1 AMU by definition, an electron is 1/2000 AMU
Radioactivity ► Structure ► Notation




                                                         +   =   20
                                                             =   10   Ne



   •   The number of electrons is equal to the number of
       protons in the nucleus therefore…
   •   The atom as a whole has no electrical charge.
   •   10 - 10 = 0
   •   The total number of protons and neutrons (nucleons)
       in an atom is called its mass (nucleon) number.
Radioactivity ► Structure ► Proton Number




                        3 protons therefore Lithium




   •   All atoms of a particular element have the same number of protons.
Radioactivity ► Structure ► Elements




                                            3 protons therefore
 1 proton therefore                         Lithium               4 protons therefore
 Hydrogen             2 protons therefore                         Berylium
                      Helium




     •   Atoms of different elements have different numbers of protons.
Radioactivity ► Structure ► Isotopes




                                      2 extra
 normal                               neutrons           3 extra
 Hydrogen          1 extra                               neutrons
                   neutron

                                  isotopes of hydrogen




    •   Atoms of the same element which have different numbers of
        neutrons are called isotopes.
Radioactivity ► Structure ► Beta Decay




   •   Radioactive isotopes (radioisotopes or radionuclides) are atoms with
       unstable nuclei. When an unstable nucleus splits up (disintegrates):

   •   It emits radiation.
   •   A different atom, with a different number of protons, is formed.
   •   For each electron emitted, a neutron in the nucleus becomes a proton.
Radioactivity ► Structure ► Fission




  •   Nuclear reactors use a process called nuclear fission. When an
      atom with a very large nucleus is bombarded with neutrons:

  •   The nucleus splits into two smaller nuclei.
  •   Further neutrons are released which may cause further nuclear
      fission resulting in a chain reaction.
  •   The new atoms which are formed are themselves radioactive.
Radioactivity ► Structure ► Comparative Energies




                                                      =
         3,500,000 g of Coal                                1 g of Uranium



 • The energy released by an atom during radioactive disintegration or
   nuclear fission is very large compared to the energy released when a
   chemical bond is made between two atoms.
Radioactivity ► Structure ► Carbon Dating




     The tomb of Rameses IX lies                     Wooden Bowl dated
     in the centre of the Valley of                     to 1000 BC
               the Kings




 •   The older a particular radioactive material, the less radiation it emits.
 •   This idea can be used to date materials, including rocks.
Radioactivity ► Structure ► Carbon Dating



             100%

            74%




                                5,000yr        10,000yr




     •   The half life of Carbon 14 is 5,730 years.
     •   During one half-life, half of the radioactive atoms initially present in
         a sample decay. This idea can be used to date materials.
Radioactivity ► Structure ► Non-Carbon Dating




                               58%
                               42%




    •   Uranium isotopes, which have a very long half-life, decay via a
        series of relatively short-lived radioisotopes to produce stable
        isotopes of lead.
    •   The relative proportions of uranium and lead isotopes in a sample
        of igneous rock can, therefore, be used to date the rock
    •   The proportions of the radioisotope potassium-40 and its stable
        decay product argon can also be used to date igneous rocks from
        which the gaseous argon has been unable to escape.
End of main section
 ► Key Terms


ELECTRICITY                        FORCE               WAVES                       SPACE                     ENERGY                           RADIOACTIVITY
Alternating current                Acceleration        Amplitude                   Artificial satellite      Conduction                       Activity
Ammeter                            Air resistance      Analogue signal             Big bang                  Convection                       Alpha
Ampere                             Braking distance    Compression                 Black hole                Efficiency                       Atom
Anode                              Centre of mass      Converging lens             Comet                     Elastic potential energy         Atomic number
Battery                            Centripetal force   Core                        Fusion                    Electrical energy                Background radiation
Capacitor                          Decelerate          Crests                      Galaxy                    Fossil fuels                     Beta
Cathode                            Drag                Critical engle              Geostationary satellite   Free electrons                   Chain reaction
Cell                               Elastic collision   Crust                       Gravity                   Generator                        Cosmic ray
Charge                             Friction            Cycle                       Light year                Geothermal energy                Count rate
Circuit breaker                    Gravity             Diffraction                 Milky way                 Global warming                   Decay
Conductor                          Kinetic energy      Digital signals             Moon                      Gravitational potential energy   Electrons
Core                               Mass                Diverging lens              Orbit                     Greenhouse effect                Electromagnetic spectrum
Coulomb                            Moment              Electromagnetic spectrum    Planet                    Hydroelectric                    Element
Current                            Momentum            Electromagnetic waves       Red planet                Kinetic energy                   Gamma
Diode                              Newton              Fetal imaging               Red giant                 Non-renewable resources          Gieger-Muller tube
Direct current                     Pivot               Fetus                       Red shift                 Power                            Half-life
Dynamo                             Speed               Focus                       Satellite                 Radiation                        Ionise
Earthing                           Terminal velocity   Frequency                   Solar system              Renewable energy                 Isotope
Electrical energy                  Thinking distance   Hertz                       Star                      Turbine                          Mass number
Electrical charge                  Velocity            Lithosphere                 Sun                       Work                             Neutron
Electric current                   Weight              Longitudinal wave           Universe                                                   Nuclear fission
Electrode                                              Magma                       White dwarf                                                Nucleon
Electrolysis                                           Mantle                                                                                 Nucleus
Electrolyte                                            Normal                                                                                 Proton
Electromagnet                                          P waves                                                                                Radiation
Electromagnetic induction                              Rarefraction                                                                           Radioactive dating
Electron                                               Real image                                                                             Radioactive decay
Electrostatic forces                                   Refraction                                                                             Radioactive emissions
Free electron                                          Seismic waves                                                                          Radioactive tracer
Friction                                               Seismograph                                                                            Radioactivity
Fuse                                                   S waves                                                                                Radioisotopes
Generator                                              Subduction zone                                                                        Random
Hertz                                                  Tectonic plates
Input sensor                                           Total internal reflection
Insulation                                             Transverse waves
Insulator                                              Troughs
Ion                                                    Ultrasound
Ionise                                                 Vibration
Joule                                                  Virtual image
Kilowatt                                               Wavelength
Kilowatt hour                                          Waves
Light-dependent resistor                               Wave speed
Logic gate
Magnet
Magnetic field              Resistor
Motor effect                Secondary coil
Ohm                         Solenoid
Output device               Thermistor
Parallel/series circuits    Transformer
Potential difference        Transistor
Potential divider           Volt
Power                       Voltage
Primary coil                Voltmeter
Processor                   Watt
Relay
Resistance
   ► Connections

                                                                                                                Output device
             Radioisotopes                                                                                                       Light-dependent
                                                       Watt          Joule     Transistor      Logic gate                            resistor            Gravity            Terminal velocity
                                                                                                            Processor
 Element                                                                                      Thermistor
                               Mass number                 Power                                                                Velocity
                     Isotope                                                  Kilowatt hour            Input sensor                                                Weight
                                       Potential divider             Energy                                                                 Decelerate
  Atomic number                                            Ohm                                                            Direction
                          Neutron                                                                Kilowatt                               Speed
                                                                                                                                                                                 Drag
         Proton                                                                                                       Relay                                Air resistance
                                    Potential difference      Resistor               Insulator                                    Graphs
                   Nucleon                                                                                                                                                         Braking
                                                           Voltage               Hertz             Cost                                      Acceleration                          distance
Background radiation                            Volt                                    Insulation              Control
                                    Nucleus                Resistance                                                                            Friction
                                                                                                                                                        Stopping       Thinking
 Chain reaction                           Electrons                                                                           Forces                    Distance       distance
                                                   Voltmeter                  Mains
      Nuclear fission Emissions Decay Atom                                                             Charge                                                  Moments     Centre of
                                                                    Voltage                                                                    Momentum
                                                                                                                                     Circular                              mass
                                               Structure                                                                                                      Mass
                           Random    Dating                                                                                   Newton
  Gieger-Muller tube                                                                                                                                                        Pivot
                                  Tracer                       Circuits                                                          Centripetal force
                            Alpha           Uses
   Count rate
                         Beta                                                                                         Cycle                          Elastic collision Kinetic energy
                                        Types            Radioactivity    Electricity                                           Hertz
   Half-life  Cosmic ray     Gamma                                                                                                         Troughs
                                                                                                                                                  Crests
                                                   Secondary coil                                         Wave speed                                          Amplitude
          Electromagnetic spectrum                                                                                        Frequency
                                                                Generator                                                            Wavelength
                                     Primary coil                                                                                                                               Normal
    Magnet                                                                                                                                               Diffraction
                                       Turbine                                        PHYSICS
                   Electrical energy                      Transformer                                           Longitudinal
    Magnetic field                                                                                                                                            Refraction       Critical angle
                                              Induction                                                                   Characteristics
     Motor effect           Solenoid                                                                              Transverse                        Total internal reflection
                                                            Energy                           Space                                                 Converging lens               Virtual image
                Electromagnetism
Global warming                                                                                                             Waves Optical                               Focus     Real image
                  Fossil fuels                                                 Big bang                                                   Diverging lens      Ultrasound
                                                               Thermal                             Solar                                                                    Fetal imaging
Greenhouse effect              Resources                                                                         Comet                             Sound
                Non-renewable                         Conduction                                 Solar system                                                              Rarefraction
                                                                     Convection      Universe                                                                 Vibration
 Geothermal
                Renewable                     Efficiency      Radiation                                                         Tectonic           Seismic                 Compression
                                                                                                        Sun
                                                                                                                                        Magma
                                                               Black hole              Red shift                                                                     Crust
        Hydroelectric                        Gravitational                     Galaxy               Planets                                      Core
                                                                                                               Orbit                                                          Lithosphere
                                   Work potential energy                                                            Electromagnetic                                  Mantle
            Kinetic energy                                       Milky way                                                               Subduction zone
                                                                                  Star              Satellite            Spectrum
                         Power
                                                         Light year                            Moon Artificial satellite                                  Seismograph
                                 Elastic potential                                 Red giant
                                       energy                           Fusion                              Geostationary
                                                                                                     Polar                                Digital signals S waves P waves
                                                                                White dwarf                          Analogue signal
ELECTRICITY ► phenomena explained by electrons

                                                                                                                                                                         ATOM small unit of matter




                                                                                                    ELECTRON part of atom, can leave                                                                                                                          PROTON part of atom, cannot leave




 PROPERTIES                                                                         MEASUREMENT                                              EFFECTS
 what features or attributes does an electron have                                  what units are used to count electrons                   things that happen because of electrons


 ABILITY TO MAKE THINGS MOVE
 charge, there are two types. negative and positive
                                                                                    WORDS FOR LARGE NUMBERS                                  MOVING ELECTRONS                                              STATIONARY ELECTRONS
                                                                                    are convenient eg the word ‘year’                        current, flow of charge, electricity                          very large numbers of electrons grouped together. static electricity, ’static’, electrostatics
                                                                                    instead of 31,536,000 seconds
 ELECTRONS HAVE A NEGATIVE CHARGE
 sometimes electrons are referred to as ‘charge’.
 The charge on proton is positive                                                                                                                                                                          EXTRA ELECTRONS                    NORMAL NUMBER OF                      LACK OF ELECTRONS
                                                                                    COULOMB                                                                                                                negatively charged                 ELECTRONS                             positively charged
                                                                                    a word for a large number of electrons                                                                                                                    no charge, neutral

 REPELLED                         ATTRACTED                                                                                                                                                                    - - - - -                           - - -                                -
 move away from other             move towards
 electrons                        protons                                                                                                                                                                     + + +                                + + +                                + + +

          - -                          -              +
                                                                                    1.          Electrons move round circuits
                                                                                    2.          A circuit is a number of components eg bulbs connected by wires                                            1. Charged objects attract neutral ones
                                                                                    3.          A battery provides a stream of electrons                                                                   2. Positive and negative objects attract
                                                                                                                                                                                                           3. Like charged objects repel




 MEASUREMENT                                         ENERGY                                        TYPES OF MOVEMENT                                                                           EASE OF MOVEMENT
 how many electrons passing a point                  electrons can deliver energy




                                                                                                   BACKWARDS AND FORWARDS                    ALWAYS ONE WAY                                    EASY                           DIFFICULT                  SOMETIMES                  IMPOSSIBLE
                                                                                                   alternating current                       direct current                                    conductor eg copper                                       DIFFICULT                  insulator eg plastic
 ELECTRONS PER SECOND                                ENERGY PER ELECTRON
 measured in amps                                    measured in volts

                                                                                                   MAINS                                     BATTERY
                                                                                                                                                                                                                                                                                      WHEN DARK
                                                                                                   delivers energy to the home
                                                                                                                                                                                                                                                                                      light dependent




                                                                                                                                                                                                                                                                      Environment
                                                                                                                                                                                                                                                                                      resistor




                                                                                                                                                                                                                                                                      Dependent
 ENERGY DELIVERED PER SECOND measured in watts, joules per second

                                                                                                   ENERGY COSTS                    EXCESSIVE ENERGY IS DANGEROUS
                                                                                                                                                                                                                                                                                      WHEN COLD
                                                                                                   MONEY
                                                                                                                                                                                                                                                                                      thermistor

                                                                                                                                                                                                                                                                        DIFFICULTY SET BY USER
                                                                                                   IF 1000 JOULES of               SAFETY MEASURES                                                                                                                      variable resistor
                                                                                                   energy is delivered per
                                                                                                   second…
                                                                                                                                                                                                                                                                        WIRE IS LONG
                                                                                                                                   INDIRECT                       DELIBERATE WEAK                AUTOMATIC OFF SWITCH
                                                                                                                                   CONTROL                        POINT
                                                                                                   …for 1 HOUR
                                                                                                                                                                                                                                                                        WIRE IS THIN
                                                                                                                                   RELAY                          FUSE                           CIRCUIT BREAKER
                                                                                                   ..the electricity company       a small safe                   when the current surges        very quick off switch
                                                                                                   call it a UNIT or               current switches               a thin section of wire
                                                                                                   kilowatthour…a unit             on a big unsafe                melts                                                                                                 POOR CONDUCTOR
                                                                                                   costs about £0.08               current                                                                                                                              fixed resistor
FORCE AND MOTION ► a push or a pull which creates movement


                                                                     OBJECTS HAVE...




 VELOCITY                                                          CONSTANT VELOCITY eg 0 m/s or 100 m/s             BALANCED FORCES                            FORCES ACTING ON THEM


                                                                   CHANGING VELOCITY                                 UNBALANCED FORCES




 SPEED m/s               DIRECTION
                                                    GRAPHS
                                                    representing   CHANGING SPEED                          CHANGING DIRECTION                                   EXAMPLES                                               CHARACTERISTICS
                                                    motion                                                                                                                                                             how can we describe a
 TIME                    DISTANCE                                                                                                                                                                                      force
 seconds                 metres
                                                                                                                                                                CONTACT           NON►CONTACT
                                                                   INCREASE                 DECREASE       TEMPORARY FORCE                   CONSTANT FORCE     FORCES            FORCES
                                                                   acceleration             deceleration   direction changes                 direction always   muscular,         field forces. gravity,
                                                                                                                                             changes            friction          magnetism
 CONSTANT SPEED


 D                   S
                                                                                                           Circular
                                                                   Mass
     T                     T                                                                               eg ball swung round on a string
                                                                                                           moon orbiting earth                                  SIZE                                       DIRECTION
                                                                                                                                                                measured in newtons


 CHANGING SPEED                                                     Momentum


 D                   S                                                                                                                                                                                                   Terminal Velocity

                                                                                                                                                                                                            friction
     T                     T

                                                                                                                                                                                                                           Friction = Weight
                                                                                                                                                                                                                           Acceleration = 0
                                                                                                                                                                                                            weight         Speed = 60 m/s
                           braking
                                                         stop
     sober, well rested, good brakes, dry road

                                          braking
                                                                       stop
     drunk, tired, bad brakes, icy road
WAVES ► movement of energy but not matter

                                                                                                       TYPES OF MOVEMENT



                                                                                                       SIDE TO SIDE                 UP AND DOWN                       A to B




                                                                                                       OSCILLATION also known as vibration



                                                                                                       KNOCK-ON EFFECTS                ISOLATED
                                                                                                       original movement               original
                                                                                                       causes movement                 movement only
                                                                                                       elsewhere


                                                                                                       WAVES




  CHARACTERISTICS                                  BEHAVIOUR                                                                                 TYPES
  how do we describe waves                         what do waves do



  How big is the oscillation?
  The AMPLITUDE is 2 metres                                                                                                                  OSCILLATION IN                                                     OSCILLATION AT 90O
                                                   CHANGE SPEED                  SPREAD OUT                      CHANGE                      DIRECTION OF                                                       TO DIRECTION OF
                                                   eg moving from air            when passing thru a             DIRECTION                   TRAVEL                                                             TRAVEL
  How long is the wave from peak to peak?          to glass                      gap: diffraction                                            longitundinal waves                                                transverse waves
  The WAVELENGTH is 5 metres



  How often does a wave pass?
  The FREQUENCY is 2 waves per second or 2 hertz


                                                   BOUNCING OFF                         BENDING                                              Sound                    SLINKY                      ROPE               SEA WAVES             ELECTROMAGNETIC
  How fast is the wave travelling?                 reflection                           light refracts when it hits glass at an                                                                                                            300,000 km/s
  The SPEED of the wave is 10 metres per second                                         angle                                                                         EARTHQUAKES




                                                   SINGLE             MANY PARALLEL WAVES
                                                   WAVE                                                                                       GAMMA           X RAY            ULTRAVIOLET          LIGHT           INFRARED          MICROWAVE             RADIO
                   AMPLITUDE




                                                                                                                                                                                                       CAN CARRY INFORMATION analogue or digital

                                                   BENT TOWARDS                           BENT AWAY FROM
                                                   each other by a convex lens            each other by a concave lens

                               WAVELENGTH




                                                                                                                                                                                     distorted wave still readable as 1 or 0


                                                                                                                                                                                                          digital is better because the message is preserved even if
                                                                                                                                                                                                          the wave is distorted
SPACE ► universe, galaxy, solar system, star, planet, satellite

                                                                                                         UNIVERSE
                                                                                                         everything we can see




 HISTORY                                                                                                 STRUCTURE                                                                                      LIFE
                                                                                                                                                                                                        Evidence for



 PAST                         PRESENT                       FUTURE
                                                                                                                                                                                                        DIRECT                                   INDIRECT

 MASSIVE                      EXPANDING                     CONTRACTION?
 EXPLOSION                                                  Big Crunch?                                  OUR GALAXY                                                 OTHER GALAXIES                      Finding live          Broadcast          Chemical changes
 Big Bang                                                                                                100 billion stars called the milky way                     100 billion                         or fossilised         signals            in atmosphere
                                                                                                                                                                                                        organisms                                Eg O2


 EVIDENCE FOR EXPANSION



 RED SHIFT
 light from distance stars has a longer wavelength                                                       STARS
 than we would ‘expect’ if universe were static                                                          massive nuclear furnaces




                   OUR STAR, THE SUN                                                                                                  ENERGY SOURCE                                     LIFE CYCLE
                   is orbited by..




                                                                                                                                      NUCLEAR FUSION
                   THE EARTH                                                         8 OTHER PLANETS                                  hydrogen and helium fusing together to create..   PAST                                PRESENT                  FUTURE
                   is orbited by..                                                                                                                                                      gravity pulls dust together.        expansive nuclear
                                                                                                                                                                                        fusion begins                       forces = gravity

                                                                                     Mercury, Venus, (Earth),
                                                                                     Mars, Jupiter, Saturn,                           HEAT AND               HEAVIER ATOMS
                   SATELLITES                                                        Uranus, Neptune, Pluto                           LIGHT                  which make life possible
                   objects held in circular path by earth’s gravity                                                                                          eg carbon

                                                                                                                                                                                                        MEDIUM STAR              BIG STAR          VERY BIG
                                                                                                                                                                                                                                                   STAR
                   NATURAL                       ARTIFICAIL

                                                                                                                                                                                                        expansive forces win over gravity

                   MOON                          USES                                                                                 TYPES OF ORBIT
                   causes tides
                                                                                                                                                                                                        STAR SWELLS              STAR EXPLODES
                                                                                                                                                                                                        into a red giant         supernova


                                                                                                                                                                                                                                                   BLACK HOLE
                                                                                                                                                                                                                                                   ultra dense, no
   MONITOR EARTH                      MONITOR SPACE                        COMMUNICATIONS                APPARENTLY FIXED IN THE SKY                   MOVES IN THE SKY                                                                            light escapes
   weather, military                  eg hubble space telescope                                          geostationary orbit                           polar orbit
ENERGY ► the ability to make things happen

                                                                                                                                  ENERGY




                                             TYPES                                                                                                                                                              CHARACTERISTICS




 POTENTIAL ENERGY stored energy                                                           KINETIC ENERGY movement energy




 LARGE SCALE can see                          SMALL SCALE can’t see                       LARGE SCALE can see                                                   SMALL SCALE can’t see                           MEASURED in joules



                                                                                                                                                                                                                CANNOT BE DESTROYED
 MATERIAL          HEIGHT                     BONDS BETWEEN           UNSTABLE            MOVING CAR                   ROTATION            CURRENT              ELECTRONS              ATOMS
 UNDER             gravitational potential    ATOMS                   ATOMS                                            of magnet           CREATES              FLOWING                VIBRATING
 TENSION           energy                     chemical                nuclear                                                              MOVEMENT             magnetic field         heat or thermal
 strain                                                                                                                                    motor                created                energy                   CANNOT BE CREATED



                                                                                                                                           MOVEMENT                                                             ENERGY CAN CHANGE
                                                                                                                                           CREATES                                                              TYPE
 eg bow and        eg water behind dam,       eg coal, gas, oil,      eg uranium                                                           CURRENT                                                              rate of change is measured
 arrow, spring     sky diver                  wood                                                                                         generator                                                            in watts




                                                                                        VIBRATIONS CAN SPREAD IN 3 WAYS


                          F
                                                                                                                                                                              STORED ENERGY eg petrol is changed into…
                                                    D                                   1. ATOMS                   2. ATOMS MOVE TO A          3. WAVE
                                 D                                                      COLLIDE WITH               NEW LOCATION                TRANSMISSION
         D                                                F
                                                                                        THEIR                      convection                  radiation
             F
                                                                                        NEIGHBOURS
                                                                                        conduction                                                                            ENERGY USEFUL TO                  ENERGY NOT USEFUL TO
                                                                                                                                                                              HUMANS                            HUMANS
                                                                                                                                                                              known as work                     known as dissipated energy
                                                                                                                                                                              eg a moving car                   eg heat from car engine
                                                                                        eg saucepan                eg boiling water            eg warmth from
                                                                                        base                                                   sun
 GREATER FORCE means greater energy
                                                                                                                                                                              maximising the useful energy
                                                                                                                                                                              makes the car EFFICIENT
 GREATER DISTANCE means greater energy




                                                                                   MAGNET MOVING                                                                       WIRE MOVING


                                                                                           S      N                                        S      N                                                             N                    S
                                                                                                                                                                          N                      S



                                                                                   Creating current without contact (Induction)
RADIOACTIVITY ► fast moving particles and high energy waves

                                                                                              ATOM
                                                                                              small unit of matter




 STRUCTURE                                                                                                                                                       STABILITY OF ATOM
 what is an atom made of




                                                                                                                                                                 STABLE ATOMS                       UNSTABLE ATOMS
 CENTRAL CORE                                                       OUTER CLOUD                                                                                  stay the same forever              break apart, pop, decay RANDOMLY
 nucleus                                                                                                                                                                                            by kicking out (emitting) particles and energy

                                                         .
 NUCLEON
 very small unit of matter                                                                                    HOW UNSTABLE IS THE ATOM?                                 FORMATION                                                  WHAT ATOMS EMIT                        BLOCKED BY

                                                         .                                                    how long does it take for…                                                                                                                                  (absorbed by)



                                                                                                              ALL ATOMS              HALF THE ATOMS




                                                                                                                                                                                                                                                                                    aluminium




                                                                                                                                                                                                                                                                                                lead
                                                                                                                                                                                                                                                                          card
                                                                                                              TO DECAY               TO DECAY                           NATURAL           UNNATURAL                                2 PROTONS & 2 NEUTRONS


                                                                                              .
                                                                                                                                                                                                                                   EMITTED
                                                                                                                                                                                                                                   alpha radiation
 PROTON                              NEUTRON                        ELECTRON                                  DIFFICULT              EASY
                                                                    smallest unit of matter                   TO PREDICT             TO
 positively charged                  not charged                    negatively charged                                               PREDICT                            bombarded with neutrons
 (exerts a force)                    (exerts no force)              (exerts a force)


                                                                                                                                                                        CONTROLLED                RAPID
                                                                                                                                                                                                                                   1 ELECTRON
                                                                                                                                                                                                                                   EMITTED
                                                                                                                                                                                                                                   beta radiation
                                                                                                                                                                                                                                                     .
                                                                                                              VERY                          VERY                        nuclear reactor           nuclear
                                                                                                              UNSTABLE                      STABLE                                                bomb
                                                                                                              short half►life               long half►life
                                                                                                                                                                                                                                   HIGH ENERGY WAVE EMITTED
                                                                                                                                                                                                                                   gamma radiation
 DESCRIPTION AND NOTATION


                                                                                                             50%                             50%
                             TYPES OF ATOM elements
                                                                                                                      1ms                            1mil. yr.

   normal atom                                               HYDROGEN ATOMS                                                                                                                                                        MEDICAL USE
                                                             always have one proton

   isotopes have
   extra neutrons
                                                                                                                                                                                                                                   alpha




                                                                                                                                                                                                                                                            INSIDE BODY
                                                             HELIUM ATOMS                                                                                                                                                          beta                                     tissue cell: live
                                                             always have two protons
                                                                                                                     Rutherford used alpha particle to show that nuclei are far apart                                              gamma
                                                             a LITHIUM ATOM
                                                             always has three protons                                                          1%                                                                                                                           damaged cell




                                                                                                                                                                                                                                     OUTSIDE BODY
                                                                                                                                                                                                       1%                                                alpha
                                   mass number
                                                                  7
                                proton number
                                                                    Li           chemical
                                                                                                                                                                                                       98%
                                                                                                                                                                                                                                                      beta
                                                                                                                                                                                                                                                                            skin cell: dead

                                                                  3              symbol
                                                                                                                                                                   protons in
                                                                                                                                                                   atoms
                                                                                                                                                                                          protons in
                                                                                                                                                                                          alpha particles
                                                                                                                                                                                                                                                         gamma
                                                                                                                       like charges repel
► Links

                                        Frequency (f)     Wavelength (λ)
                                                                   Acceleration (a)     Time (t)



                            Mass (m)              Velocity (v)

  Gravitational Field
  Strength (g)                          Momentum
                                                                                      Current (I)


                                                        Force (F)                              Resistance (R)
                                         v2                                                                     Charge (Q)
                              ½m
             Weight (w)                 Distance (d)
                                                                 Impulse                  Voltage (V)
  Change in                                      Moment
  Height (Δh)
                                                                            Power (P)


                      GPE     KINETIC              WORK              ELECTRICAL       ELECTRICAL

                                                        Energy (E)
Efficiency                                                                                                  Unit Cost


              Useful Energy                                                                             Total Cost

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:17
posted:11/3/2012
language:English
pages:163