Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Explain the dangers of providing any connection between the live wire and…
Full specification wording
Topic 10 – Electricity and circuits: 10.41 Explain the dangers of providing any connection between the live wire and earth
The live wire is at a high potential relative to earth, which is held at about 0 V. If any conducting path links the live wire to earth, a large current flows through that path.
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 39 of 39
Study notes
From the checked teaching notes for this specification point.
The idea
The live wire is at a high potential relative to earth, which is held at about 0 V. If any conducting path links the live wire to earth, a large current flows through that path. A person touching the live wire while also in contact with earth becomes part of that path, so current passes through the body and can cause a severe shock, burns, or death. The low resistance of the body-to-earth route allows a current far above the small value that is dangerous to a person. A metal appliance casing wrongly connected to live becomes live, so touching it while earthed gives the same shock. Earthing the casing and using fuses or circuit breakers reduce the danger by giving fault current a low-resistance route and by disconnecting the supply.
What earns the marks
- States that the live wire is at a high potential relative to earth, which is at about 0 V.
- Explains that a connection between live and earth creates a low-resistance path so a large current flows.
- Describes that a person touching the live wire while earthed completes the path, so current flows through the body.
- Identifies the consequences for a person as electric shock, burns or death.
- Explains that a metal casing connected to live becomes live and gives a shock when touched.
- States that earthing the casing and using a fuse or circuit breaker reduce the danger.
Common mistakes and how to put them right
Claims that the earth wire carries the normal operating current.
Put it right by stating that the earth wire carries current only in a fault.
Says the live wire is safe to touch because it is insulated.
Put it right by noting that damaged insulation or direct contact removes that protection.
Confuses the live wire with the neutral wire.
Put it right by stating that the neutral is near earth potential while the live is at high potential.
Exam tips
- Link the danger to a complete path: live, the person, earth, and back to the supply.
- Name the outcome for the body, such as shock, burns or death, rather than saying only that it is dangerous.
- Mention how earthing and a fuse or circuit breaker protect the user, since this shows understanding of the fault path.
Try the lesson
The start of the Topic 10 – Electricity and circuits: 10.41 Explain the dangers of providing any connection between the live wire and earth lesson, made from checked teaching notes for this specification point.
Have a go first
Why is it dangerous if a person's body forms a conducting path between the live wire and earth?
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