A 12 ohm resistor has a current of 0.50 A flowing through it. Calculate the potential difference across the resistor.
[2 marks]
Total for this question: 2
All equation deep-dives
Ohm's law and electrical power
Electricity
AQA 8463
On the equation sheet
ORIGINAL
V = I R and P = I2 R
Two equations, one topic — and P = I^2 R needs the current squared, not doubled.
Current GCSE 8463 policy: The full AQA GCSE Physics 8463 equation sheet is provided with both papers in 2026; use fluency practice to learn selection and rearrangement, not to memorise the list.
Board and spec code confirmed against AQA 8463 · registry checked 2026-07-17How this checking works
Know the equation
| Symbol | Quantity | Unit |
|---|---|---|
| V | potential difference | V |
| I | current | A |
| R | resistance | ohm |
| P | power | W |
Rearrangements
- I = V / R
- R = V / I
- P = V I
- P = V2 / R
- R = P / I2
Apply it — mark your own working
Work each one out on paper first, then reveal the mark scheme and tick the marks you actually earned. That is exactly how you should mark past papers.
Q1
Do the calculation on paper first — then mark it.
Q2
A resistor of resistance 20 ohm carries a current of 3.0 A. Calculate the power dissipated in the resistor.
[2 marks]
Total for this question: 2
Do the calculation on paper first — then mark it.
Where the marks get lost
- In P = I2 R, doubling the current instead of squaring it.
- Mixing up which quantity is which — label V, I and R from the question before substituting.
- Leaving resistance in kilo-ohms; convert to ohms first (1 kohm = 1000 ohm).
Exam tip: If a question gives you current and resistance and asks for power, go straight to P = I2 R rather than finding V first — it is one step, not two.
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