ELECTRICITY
Notes vs Discussion
• In this chapter we will write out our class
notes
– Your are to write any information that is in
RED
– Anything in black does not need to be copied
by you.
– Your outline will only consist of practice
worksheets and lab activities for this chapter.
Atom ATOMIC
BOMB
Nucleus NUCLEAR
POWER
Electron Electricity
The ATOM
Electrons
The atom is made of 3
(Negatively charged)
basic parts:
1. Protons
2. Neutrons
3. Electrons
Nucleus The nucleus contains
both protons and
neutrons together.
Neutrons
(Neutral charge)
Protons
(Positively
charged)
HYDROGEN
(Proton)
Nucleus
Protons
Neutrons
NUCLEUS + ELECTRONS = ATOM
# PROTONS = # ELECTRONS
# PROTONS > # ELECTRONS
Missing Electron
# PROTONS < # ELECTRONS
Extra Electron
Electric charge
• 3 Types of electrical charge
• Positive - more protons than electrons
• Negative - more electrons than protons
• Neutral - same amount of protons and
electrons
More about atoms!!!!!!
Atoms become “charged” when
they gain or lose electrons
• Gain electrons - become negatively
charged
• Lose electrons – become positively
charged
• Protons do not move from atom to
atom.
• The natural state of any atom is to be
neutral.
– Charged atoms in a liquid are called IONS
Law of Electrical Charges
Different charges attract
Same charges repel
Demo
Another way to show
attract and repel
The act of repelling or attracting occurs
because of Electric Forces
Why does a
balloon
stick to the
wall?
Why does
your hair
do this??
Each hair
becomes
negatively
charge and
therefore
REPELS
each other.
Electric Discharge
-The rapid movement of excess
charge from one place to another.
• 2 Forms of Discharge
– Sparks (Small discharge)
– Lightning bolts (Large discharge + million
volts)
Flash Gallery
Lightning form
Lightning
- a large electrical discharge
between the atmosphere and
ground.
• 3 ways lightning can strike
– Cloud to ground
– Ground to cloud
– Cloud to cloud
Formation of Lightning
1. Collection of negative charges in cloud.
2. Ground becomes positive.
3. Stepped leader forms in between and
makes connection with ground
4. Invisible discharge takes place
5. Return stroke that we see.
1. 4 – 6 return strokes can take place during one
strike.
+++++++++++++++++++++++++++++++
Positively charged at the top
___ ___Negatively charged towards bottom ___ ___ ___
___ ___ ___ ___ __ __ __ __ __ __ __
Stepped Leader
The lightning we forms first
see “return stroke”
++++++++++++++++Positively charged ground++++++++++++++++++++++
Invisible
Channel is very
jagged and
unpredictable.
Types of Lightning
• Ribbon lightning
Ball Lightning
Sheet Lightning
Bead Lightning
Red Sprites
Blue jets
Lightning and Thunder
5 miles for every second counted
Electric Circuits
Circuit – A closed conducting pathway
for electrons to flow through.
The “flow of electrons” is called
Electric current
Electric current
is a lot like the
flow of water
through pipes
Simulation
Simple Circuits
• 3 parts to a simple Circuit
–1. Source of Electricity
»“battery”
–2. Conductor
»“wire”
–3. Load
»“Light bulb or motor”
»What electrons do work on
Draw in your notes!!!!!
Source
+
_
Conductor
Load
Batteries and Bulbs
“Student Challenge!!!!!!”
Can you and your partner work together to make the
light bulb light up!!!! Use only the battery, bulb (with no
socket, and a piece of wire. There are ten different
combinations. Try to figure out all ten. You must make
a drawing of how you arrange the items to make the
bulb light using the symbols below. Good Luck!!!
Clue # 1
Touch here
Touch here
Clue #2
Clue #3
Conductors
Materials that allow electrons to flow easily.
We use these materials in electrical circuits.
silver
copper
gold
aluminum
iron
steel
brass
bronze
mercury
graphite
dirty water
Insulators
Insulators don't allow electrons to flow easily.
We use these materials to protect ourselves.
glass
rubber
asphalt
fiberglass
cotton
paper
wood
plastic
air
Argon gas
Tungsten Filament is double coiled to
allow for up to 30 feet of wire give off
the glow.
Source of Electricity (Battery)
•Supplies electrical potential energy to a circuit.
•Sets the voltage of the circuit.
2 types of batteries
Dry Cell Wet Cell
Wet Cell versus Dry Cell
•Used in automobiles •Used in small electronic
equip.
•High voltage (12v) •Low voltage ( 1.5v)
•Short life •Long life
•Needs recharged often •No recharging
•Liquid electrolyte (salt •Manganese paste
or acid) electrolyte
Electrical Symbols
•Source •Voltmeter
•Light bulb •Ammeter
•Motor •Resistance
•Switch on •Fuse
•Switch off
Series Circuits – a circuit that has
only a single path (one loop) for
current to flow through all of its
parts.
Bulbs in Series
Batteries in Series
Parallel Circuits - requires more
than one path for current flow in
order to reach all of the circuit
parts.
Batteries in Parallel
Fuses and Circuit Breakers
Devices that open a circuit due to overload.
(drawing to much current)
* prevents damage or potential fire
Fuses – open a circuit when a
narrow filament melts. Not
reusable.
New Fuse Blown Fuse
Breakers – a switch that automatically opens
a circuit when overload occurs. Reusable
Switch can be opened 3 different ways.
1. heat from circuit causes
bimetallic strip to separate 2 metals.
2. electromagnet breaks circuit
3. small explosion
Calculating Electrical Cost
Step 1 – Calculate wattage (volts X amps)
220 volts X 3 amps = 660 watts
Step 2 – Convert watts to Kilowatts (X .001)
or divide by 1000
660 X .001 = .66 kilowatts
Step 3 – Multiply kilowatts by the amount of
time used. All numbers must be in hours.
.66 kilowatts X 3 hours = 1.98 Kilowatt - hours
Step 4 – Multiply Kilowatt – hours by the
rate or price (around $0.10)
1.98 X .10 = $0.19