Electricity Flashcards
(20 cards)
What is electric current?
A: The flow of electric charge (electrons) around a circuit. It is measured in amperes (A).
A circuit has a current of 2 A flowing for 5 minutes. Calculate the charge that flows. (Exam style)
Convert time: 5 min x 60= 300 s
Q = I × t = 2 × 300 = 600 C
Does current get “used up” as it moves through a circuit?
No – current is the same at all points in a series circuit. It is not used up.
What is the equation for charge flow?
Q = I × t
Q = charge (C)
I = current (A)
t = time (s)
What is resistance?
Opposition to current flow, measured in ohms (Ω).
State Ohm’s Law.
A: V = I × R
V = voltage (V)
I = current (A)
R = resistance (Ω)
Describe the current-voltage graph of an ohmic conductor.
A straight line through the origin – current is directly proportional to voltage
Explain why the resistance of a filament bulb increases as current increases. Extension (4marks)
Current increases → filament heats up
Particles in filament vibrate more
More collisions with electrons
Therefore, resistance increases with temperature
In a series circuit: how is current and potential difference shared?
Current: same at all points
Voltage: shared between components
In a parallel circuit: how is current and potential difference shared?
Voltage: same across each branch
Current: splits across branches (adds up to total at the battery)
If you add more resistors in parallel, what happens to total resistance? (Common trap)
It decreases – because more paths allow more current to flow.
12 – 6 Mark Practice Question (Common!)
Compare the current, voltage, and resistance in series and parallel circuits. Include what happens when you add more resistors in each.
A (Structure):
Series: Current same, voltage shared. Adding resistors increases total resistance.
Parallel: Voltage same, current splits. Adding resistors decreases total resistance (more paths).
Example values help gain full marks.
What is the frequency and voltage of UK mains electricity?
230 V, 50 Hz
What type of current is mains electricity?
AC (alternating current) – changes direction regularly.
What current is supplied by a battery?
DC (direct current) – flows in one direction only.
Name the three wires in a UK plug and their colours.
Live – Brown
Neutral – Blue
Earth – Green/yellow
Safety Question (3 marks)
Explain the role of the earth wire in a plug.
Carries current to ground if fault occurs
Prevents metal case becoming live
Protects user from electric shock
Why is the fuse connected to the live wire?
So it will break the circuit if too much current flows, stopping electricity entering the appliance
A kettle uses 230 V and draws 10 A. Calculate its power.
P = V × I = 230 × 10 = 2300 W
Equation List (Know All!)
Q = I × t
V = I × R
P = V × I
P = I² × R
E = P × t
