Electricity
Electricity
Electricity occurs in 2 different forms
• Static
• Current
Current Electricity
• Moving electricity
• Electrons flow through a
conductor - material that allows
electrons to flow through
• Circuit = continuous loop for
electrons to flow
• Needs energy supply
Electrical components
• Wire
• Ammeter
• Battery
• Fuse
• Connected
wires
• Bulb
• Switch
• Voltmeter
• diode
• Resistor
• Rheostat
CIRCUIT TYPES
The simplest type of circuit involves
electricity going around with no “choices”
(electrons don’t really choose).
This is called a Series circuit.
Draw the path the electrons travel-out the
negative toward the positive
The other main type of circuit has two or
more branches.
This is called a Parallel circuit.
Draw on the electron flow.
What sort of circuit is this?
A parallel… but, more
importantly…
A short circuit.
Series circuit
• Has a single loop for electrons to
travel round
• Components are connected one after
another
• Current has to travel through all
components
• Current is the same at all points
• Voltage is shared between
components
• It is either all on or all off
Series circuit
• http://www.ndted.org/EducationResources/High
School/Electricity/seriescircuit.
htm
Parallel circuit
• Has two or more paths for
electrons to flow down
• Current is shared between the
branches
• Sum of the current in each
branch = total current
• Voltage loss is the same across
all components
Practice
• http://lgfl.skoool.co.uk/keystage
3.aspx?id=93
Current (I)
Current is the flow of electrons
around a circuit
• DC = direct current like battery
• Electrons flow in one direction
• AC = Alternating current like
mains
• Electron flow changes direction
50x per second
Ammeter
•
•
•
•
Measures CURRENT(I)
Unit = Amp (A)
Current is flow of electrons
Connect in series at the point
you wish to measure
Voltage (V)
Gain or loss of energy as it
passes through a component
• Voltage lost = voltage gained
• In series voltage loss is shared
between components
• In parallel voltage loss is the
same across all components
Voltmeter
• Measures voltage
• Unit = Volt (V)
• Voltage increases as it passes
through energy suppliers
• Voltage is decreased as it
passes through users
• Connect in parallel around a
component
SUMMARY
In Series
Current
Voltage
Always the same
Voltage from source =
voltage used
Voltage is shared
between power users
In Parallel
The branches share
electrons and add to the total
Voltage is the same in all
branches
Resistance (R)
The amount that a component
slows the current
•As the electrons are slowed by a resistor, energy is
lost in the form of heat.
•This means that current, resistance and voltage must
be linked.
•This is Ohms law
•The unit of resistance is the ohm, symbol 
V
I × R
Power
Energy used by component per
second
• Unit of power is the Watt, symbol is W
• One watt means that 1 joule of electrical
energy is being used up per second.
• Current, voltage and power
are linked
P
I × V
Electricity Generation
• Brainstorm ways to generate
electricity
Fossil Fuels
Hydro Dam
Hydroelectric power
Nuclear power
Wind Power
Tidal Power
Geothermal
Solar
• Solar water heating
• Photovoltaic cells
• Solar furnace
PROBLEMS
1. Fill in the gaps in the table.
a
b
c
d
e
g
i
k
j
f
h
l