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Electrical Circuits Revision
P2 REVISION – CHAPTER 4 – Current Electricity
Electrical Charges
If you rub two electrically
insulating materials are rubbed
together, __________________
are rubbed off one material and
deposited on the other.
Objects that have opposite electric
charges ______________ each
other, if they have the same
electric charge they___________.
Electric Circuits
Electric symbols
I is the current in amperes, A
Q is the charge in coulombs, C
t is the time in seconds, s.
Every component has an agreed circuit
symbol.
Make sure you can recognise and draw
them!
Resistance
Current is measured with an ammeter. Where are ammeters placed in relation to the
component?
What is the unit of current?
The potential difference(pd) across a component is measured with a voltmeter. These
are always placed in parallel with the component. What is the unit of potential
difference?
V is ?
W is ?
Q is ?
Don’t forget units!
R is ?
V is ?
I is ?
Don’t forget units!
Ohm’s law: states that the current through a resistor at constant temperature is
directly proportional to the potential difference across the resistor.
KEY WORDS:
Insulating
Electron
Attract
Repel
Resistance
Series
ASSESSMENT:
P2 REVISION – CHAPTER 4 – Current Electricity Cont.
Series Circuits
Current-Potential Difference Graphs
A current-potential difference
graph for a resistor.
How are the components connected in a series circuit?
What happens if there is a break in the circuit?
Is the current the same or different through each component?
If you add together the potential difference what does it give you?
The resistance of the individual
components add up to give the
total resistance of the circuit.
A current-potential difference
graph for a filament bulb, line is
a curve so the current is not
directly proportional to the
__________________
___________________.
The current in a diode flows
in one direction only, in the
reverse direction the diode
has a very high resistance so
the current will be what?
Parallel Circuits
How are the components connected in a series circuit?
What happens if there is a break in the circuit?
Is the pd across each component the same or different?
The bigger the resistance of a component, the ______________ the current through it.
Use this equation to work out the
current through a component in a
parallel circuit.
Thermistor: Resistance _______________ if its temperature
increases.
LDR: resistance decreases if the light intensity on it ___________.
KEY WORDS:
Diode
Filament bulb
Resistor
Thermistor
ASSESSMENT: