Electricity
Science, Physics. Usually met in years 8 to 11.
Use potential difference, current, resistance, power and energy transferred.
What you practise
- V = I × R
- Power = current × potential difference
- Energy = power × time
Finishes with energy in joules from power and minutes. Practice moves up a level when a round goes well and down when it does not.
Sample questions
Each sample comes with the method and the reason every wrong option is wrong. Real practice rounds are ten questions at your level.
Sample question, level 2 of 5
A potential difference of 27 V drives a current of 3 A through a component. What is its resistance?
- 9 Ω
- 81 Ω
- 6.75 Ω
- 0.111 Ω
- 24 Ω
Show the answer and method
Answer: A, 9 Ω
The method: R = V ÷ I = 27 ÷ 3 = 9 Ω.
Why the other options are wrong:
- B, 81 Ω: The potential difference was multiplied by the current. Resistance = potential difference ÷ current.
- C, 6.75 Ω: Close, but check the division.
- D, 0.111 Ω: The division is upside down. Resistance = V ÷ I.
- E, 24 Ω: The current was subtracted from the potential difference.
Sample question, level 4 of 5
A device has a current of 9 A at 6 V. What is its power?
- 15 W
- 540 W
- 1.5 W
- 54 W
- 0.667 W
Show the answer and method
Answer: D, 54 W
The method: Power = current × potential difference = 9 × 6 = 54 W.
Why the other options are wrong:
- A, 15 W: The current and potential difference were added.
- B, 540 W: The decimal point is one place out.
- C, 1.5 W: The division is upside down. Power = current × potential difference.
- E, 0.667 W: The potential difference was divided by the current. Power = current × potential difference.
See where this fits: GCSE science with AQA and Key Stage 3.
Related topics: Density, Forces, Energy, Waves.
