AQA GCSE Physics
AQA GCSE Physics 4.2.3 Domestic Uses and Safety Exam Questions
Free AQA GCSE Physics exam questions for 4.2.3 Domestic Uses and Safety, with a mark scheme for every pack. Covers direct and alternating potential difference, UK mains supply, three-core cables, live, neutral and earth wires, and electrical safety.
4.2.3 Domestic Uses and Safety exam questions
3 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA GCSE Physics 4.2.3 Domestic Uses and Safety
This AQA GCSE Physics section covers the electricity supplied to homes. You need to know the difference between direct and alternating potential difference, the UK mains frequency and voltage, the colours and roles of the wires in a three-core cable, and why touching the live wire is dangerous. It is examined on Paper 1. Examiners regularly ask why the live wire is dangerous even when a switch is open, and what each wire does, so precise wording matters.
What you need to know
- Direct and alternating p.d. Cells and batteries supply direct current (dc), which flows in one direction. Mains electricity is an alternating current (ac) supply, which repeatedly reverses direction.
- UK mains supply In the UK the domestic mains supply has a frequency of 50 Hz and is about 230 V.
- Three-core cable Most appliances use three-core cable. Live wire: brown. Neutral wire: blue. Earth wire: green and yellow stripes.
- Roles of the wires The live wire carries the alternating potential difference from the supply. The neutral wire completes the circuit and is at or close to earth potential (0 V). The earth wire is a safety wire that only carries current if there is a fault, and is at 0 V.
- Danger of the live wire The live wire is at about 230 V. Touching it makes a large potential difference across your body, so a current flows through you to earth, giving an electric shock which can be fatal.
- Switch open but still dangerous Even when a switch is open, the live wire may still be at a high potential, so touching it can cause a shock. Any connection between the live wire and earth can be dangerous.
Common mistakes in 4.2.3 Domestic Uses and Safety
- Saying the earth wire normally carries current. It only carries current if there is a fault.
- Getting the colours wrong. Live is brown, neutral is blue, earth is green and yellow.
- Saying the neutral wire is at 230 V. It is at or close to 0 V; the live wire carries the 230 V alternating p.d.
- Saying the danger comes from 'the voltage going through you'. A potential difference across the body causes a current to flow through it.
Try three 4.2.3 Domestic Uses and Safety exam-style questions
1. State the frequency and potential difference of the UK mains supply. (2 marks)
Show the mark scheme answer
50 Hz; about 230 V.
2. Describe the difference between direct and alternating potential difference. (2 marks)
Show the mark scheme answer
Direct p.d. stays in one direction (constant polarity) so current flows one way only; alternating p.d. repeatedly reverses direction, so the current changes direction.
3. Explain why a person touching a live wire can receive an electric shock even if the appliance is switched off. (3 marks)
Show the mark scheme answer
The switch may be open but the live wire is still at a high potential (about 230 V); the person is at earth potential (0 V); so there is a large p.d. across their body and a current flows through them to earth.
4.2.3 Domestic Uses and Safety FAQs
What does AQA GCSE Physics 4.2.3 Domestic uses and safety cover?
It covers direct and alternating potential difference, the UK mains supply, the three wires in a mains cable and why the live wire is dangerous.
Which paper is domestic electricity examined in?
It is part of the Electricity topic on AQA GCSE Physics Paper 1.
What facts must I memorise for this section?
Learn 50 Hz and about 230 V, the colours brown, blue and green and yellow, the potential of each wire, and why the earth wire only carries current in a fault.
