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Safety Devices — How They Protect You

Part of Mains Electricity & Safety · GCSE GCSE Physics revision

This deep dive covers Safety Devices — How They Protect You within Mains Electricity & Safety for GCSE Physics. Revise Mains Electricity & Safety in Electricity for GCSE Physics with 18 exam-style questions and 30 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 4 of 16 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 4 of 16

Practice

18 questions

Recall

30 flashcards

🛡️ Safety Devices — How They Protect You

FUSE:

  • Thin wire that melts if current is too high
  • Breaks the circuit, cutting off power
  • Common ratings: 3 A, 5 A, 13 A
  • Must be on the LIVE wire (cuts the dangerous wire)
  • Choose fuse slightly ABOVE normal operating current

CIRCUIT BREAKER:

  • Switch that automatically "trips" if current too high
  • Can be reset (unlike fuses which must be replaced)
  • Reacts faster than fuses

EARTH WIRE + FUSE (working together):

  1. Fault occurs — live wire touches metal case
  2. Earth wire provides low-resistance path to ground
  3. Large current flows (much larger than normal)
  4. Fuse melts, breaking the circuit
  5. Power cut off before user can be harmed

Keep building this topic

Read this section alongside the surrounding pages in Mains Electricity & Safety. That gives you the full topic sequence instead of a single isolated revision point.

The Three Wires — What They DoDouble InsulationWhy the Earth Wire Saves LivesUK Mains Supply — Key Facts

Practice Questions for Mains Electricity & Safety

What does AC stand for, and how does it differ from DC?

  • A. Alternating current; it flows at a higher voltage than DC
  • B. Alternating current; it repeatedly changes direction, whereas DC flows in one direction only
  • C. Adapted current; it is produced only by batteries
  • D. Alternating current; it flows at a constant rate, whereas DC changes direction
1 markfoundation

Explain how a fuse protects an electrical circuit from damage.

2 marksstandard

Quick Recall Flashcards

What is DC?
Direct Current — current flows in one direction only (batteries provide DC)
What is AC?
Alternating Current — current direction reverses constantly (50 times/second in UK)

18 questions on Mains Electricity & Safety — practise free

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The Three Wires — What They Do

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Double Insulation