I
I
I
V
As temperature increases,
resistance increases
Filament Lamps
Measured
in Volts
Potential
Difference (V)
Rubbing insulating
materials together rubs
electrons off one material
and onto the other
Material gaining
electrons becomes
negatively charged
KEY
‘Physics only’
written in clouds.
Resistors
Current can only flow
in one direction
Diodes
Applies at constant
temperature
TOPIC 2: ELECTRICITY
Charged object
produces an electric
field around itself
Field lines point from
positive to negative
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Current is directly
proportional to
Potential Difference
Ohmic Conductors
I-V Characteristics
Static Electricity
V
Resistance stays
constant
V
Mains Electricity
Earth Wire
Green and yellow
stripes
Prevents
appliance from
becoming live
Live Wire
Neutral Wire
Brown
Blue
Completes the
circuit
Mains electricity
voltage is 230V
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The rate of flow
of charge
V=IR
Current (I)
How hard it is for
current to flow
Measured in
Ohms
E=Pt
Measured in
Watts
Rate of
energy transfer
Power (W)
Resistance (R)
E=QV
Measured in
Coulombs
Measured
in Amps
Electrical Quantities
& Conductors
Q=It
Charge (Q)
Higher voltage
reduces energy loss
Current is
constant
Direct Current
TOPIC 2: ELECTRICITY
National Grid
Transports current at very
high voltages
R = R₁ + R₂
Current flows in
one direction
Series Circuits
Can only flow if there
is a source of
Potential Difference
Power Lines
P=I²R
P=IV
Step-Down
Transformers
Circuit
Arrangements
Alternating Current
Step-Up
Transformers
Voltage
decreases
Used between power lines
and houses
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Voltage
increases
Direction of
current flow
continually
changes
Used between power
stations and power lines
Parallel Circuits
Current is
split between
branches
Potential Difference
across each branch is
the same
1/R = 1/R₁ +1/ R₂
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