Back to Daily Question archive

A2 Daily A Level Physics question

2026-04-12 OCR A Fields: Gravitational, Electric & Magnetic (M5/M6) 4.2.2(a) 4.2.2(b) 4.2.2(c)

A 1.0 kW electric kettle operates from a 230 V (r.m.s.) sinusoidal mains supply. Treat the heating element as a fixed resistor at operating temperature. Which is the best estimate of the peak current through the element when running at its rated power?

  1. A 3.1 A
  2. B 4.3 A
  3. C 6.1 A (correct)
  4. D 8.7 A

Answer

The correct answer is C.

Correct: C — 6.1 A. The effective current is about 1000/230 ≈ 4.35 A, and for a sine wave the peak is √2 times larger, giving ≈ 6.1 A. A 3.1 A is obtained by incorrectly dividing the effective current by √2 instead of multiplying. B 4.3 A is the effective (r.m.s.) current, not the peak. C is the correct value as above. D 8.7 A is roughly twice the effective current, confusing peak with peak-to-peak or assuming an incorrect factor.

Try today's guest Daily MCQ A Level Physics MCQ practice Problem-solving previews