Denny High School Physics Department

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					                                  Denny High School Physics Department

                                          Standard Grade Revision


                                               Using Electricity


Section 1                    Revision of Second Year


   1. Draw symbols for a battery, fuse, lamp, resistor, capacitor, diode and variable resistor.




Section 2                    Charge and Current


   1. When an electric current flows, what kind of particle actually flows through the wire?



   2. What unit is used to measure electric current?


What instrument is used to measure current?



   3. A circuit is assembled to measure the current flowing through a bulb when it is connected to as battery.
      Draw the circuit diagram of the necessary circuit.




   4. Find the size of the missing currents below.
C5. Write down the equation that links charge, current and time. Write down the unit (and abbreviation) that is
used to measure each quantity.




C6. What unit is used to measure electrical charge?




Section 3                     Voltage


   1. What unit is used to measure voltage?


What instrument is used to measure voltage?



C2. The voltage of a supply is increased from 2V to 4V. How would this change effect the amount of energy
that is given to the charges flowing in the circuit?




   3.A circuit is assembled to measure the voltage across a bulb when it is connected to as battery. Draw the
   circuit diagram of the necessary circuit.




   4. Find the size of the missing voltages below.
Section 4                     Resistance


   1. What unit is used to measure resistance?



   2. Look at the circuit below.




The resistance of the variable resistor is increased. How would this change effect
           (i)     the reading on the ammeter
           (ii)    the brightness of the bulb?




   3. Describe how you can measure the resistance of your body using an ohmmeter.




How would running your hands under a tap prior to the experiment effect the measured resistance of your body?




   4. Write down two uses of a variable resistor.
   5. Write down the equation that links resistance, current and voltage. Write down the unit (and
      abbreviation) that is used to measure each quantity.




C6. Write down the laws for finding the combined resistance of a number of resistors
           (i)   in series and
           (ii)  in parallel




Find the combined resistance of the following: -




Section 5                    Energy and Power


   1. Write down the units of (i) energy and (ii) power.


How are these two units related?
2. Write down the equation that links power, energy and time. Write down the unit (and abbreviation) that
   is used to measure each quantity.




3. Write down the equation that links power, current and voltage. Write down the unit (and abbreviation)
   that is used to measure each quantity.




C4. Write down the equation that links power, current and resistance. Write down the unit (and
abbreviation) that is used to measure each quantity.




6. What happens to a wire when an electric current is passed through it?




7. Complete this table that describes filament bulbs and tube lamps.
                                                Filament                   Tube
      Energy change
      Where energy change takes place
      Amount of heat produced
      Cost to buy
      Cost to run
Section 6                     Car Wiring


C1. Draw the circuit diagram for a car wiring system with the following specifications: -
Four sidelights, two headlamps, a horn and a heater.
All should be controlled by their own switch.
The headlamps and the heater should only work if the ignition switch is closed.




Section 7                     AC



1. What do the terms ac and dc stand for?


Explain the difference between ac and dc currents.




   2. Which of these types of current is supplied from the mains?


Which of these types of current is supplied from batteries?




C3. The stated value of a power supply is 12V AC. Is the peak value of the supply higher or lower than this
value?
Section 8                     Domestic Electricity


1. State the voltage of the mains supply.



2. State the frequency of the mains supply.



     3. What kind of energy is supplied from the mains?


Write down the energy change that takes place in the following appliances: -

Food mixer

Radio

Washing machine

TV

Cooker



     4. Name three appliances used in the home to change electrical energy into heat energy.




     5. Find out the approximate power ratings of the following appliances: -

Light bulb

TV

Hairdryer

Foodmixer

Kettle


     6. The flex that is used for an appliance depends on its power rating. Write down the “700 W rule”.



Write down whether you would choose a 3A or a 13A flex for each of the appliances above.
   7. What is the purpose of the fuse in a plug?

What does the fuse protect?


   8. Write down whether you would choose a 3A or a 13A fuse for each of the appliances above.




   9. What are the names of the three wires found inside most flex used in the home?


What are the colours of the insulation surrounding each of these wires?




   10. Which of these wires is used as a safety device?



C11. Explain in detail how an earth wire works.




   12. Name the type of appliance that does not require an earth wire.



   13. Draw the double insulated symbol.




C14. Explain why it is dangerous to put fuses or switches in the neutral wire rather than the live wire.
   15. Draw a circuit diagram of a continuity tester that could be used to check whether a fuse had blown.




   16. Explain why it is dangerous to touch an electrical appliance with wet hands.




Why is it dangerous to connect a mains appliance to the lighting circuit?




   17. Why is it dangerous to connect too many appliances to one socket?




   18. Does house wiring connect appliances in series or parallel?




C19. Draw a circuit diagram to show how mains appliances are connected in a ring circuit.




C20. What is the main advantage of a ring circuit over a normal parallel circuit?




C21. Write down two differences between the power circuit and the lighting circuit used in homes.
22. What is the purpose of the mains fuses?



What does the mains fuses protect?



23. Name the device that could be used instead of a mains fuse.




C24. Write down two advantages that this device might have over a mains fuse.




25. What unit is used to measure the energy used by a home?




C26. Calculate how many joules of energy are contained in one of these units.




Section 9                    Movement from Electricity



1. Describe how you could build an electromagnet.




   2. Name two devices that contain electromagnets.
   3. Look at the diagram below.




Explain what happens to the wire when the switch is closed.




C4. What two changes could be made to the set-up of the apparatus to allow the wire to move in the opposite
direction?




   5.On the diagram below, label the brushes, the commutator, the rotor and the magnets.




C6. Use your diagram to explain how the motor works.
C7. Write down the use of the following parts of a commercial motor.

Brushes

Commutator

Field Coils

Rotor

				
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