A fuse and a circuit breaker can both be used as safety devices in mains electrical appliances. Explain how a fuse protects an appliance when the current becomes too high, and state two advantages of using a circuit breaker instead of a fuse.

Pearson Edexcel International GCSE Physics (4PH1) — 2.1 Mains electricity · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

A fuse contains a thin metal wire or filament that melts when the current exceeds its rating, breaking the circuit and cutting off the power to the appliance.

A circuit breaker can be reset and used again, whereas a fuse must be replaced.

A circuit breaker operates faster than a fuse, interrupting the current more quickly.

Examiner tips

  • Use the word "melts" to describe the fuse action. Mention that the fuse breaks the circuit. State that a breaker can be reset and that it is faster. Keep each point concise to fit the 4 marks.

Common mistakes

  • Saying the fuse only 'trips' instead of 'melts'. Forgetting to mention that a fuse must be replaced. Confusing the speed of operation with the reset ability.

Mark scheme (4 marks)

  1. A fuse contains a thin metal wire/filament that melts/breaks when the current exceeds its rating
  2. This breaks/disconnects the circuit, cutting off the current/power supply to the appliance
  3. A circuit breaker can be reset and used again (whereas a fuse must be replaced)
  4. A circuit breaker operates/acts faster than a fuse

Key terms in this question

fuse · circuit breaker · current

Related

More Mains electricity questions

▶ Try answering this question with AI marking (free) →