GCSE Physics (CCEA)

Topic Summaries

Electricity

Three-core cables

  • Most electrical appliances connect to a wall socket using cables containing three wires:
    • A live wire, which carries an alternating potential difference of 230 V from the mains supply.
    • A neutral wire, which completes the circuit and has a potential difference of close to 0 V.
    • The earth wire, which has a potential difference of 0 V. It is a safety wire which only carries current in case of a fault.

  • There is a large potential difference between us and the live wire, so touching it would cause a current to flow through us and give us an electric shock.
  • If the live wire touches a metallic appliance, then the earth wire is used to carry the resulting current away.

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