Domestic Uses of Electricity

This lesson covers the domestic uses of electricity, including alternating and direct current, the structure of a three-pin plug, the function of the earth wire and fuses, and the role of circuit breakers. This is part of the AQA GCSE Physics specification (4.2.2).

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Alternating Current (a.c.) and Direct Current (d.c.)

There are two types of electric current:

Direct Current (d.c.)

Direct current always flows in the same direction. The current has a constant value (for a steady d.c. supply).

Sources of d.c.:

• Batteries and cells
• Solar cells
• Phone chargers (which convert mains a.c. to d.c.)

Alternating Current (a.c.)

Alternating current continuously changes direction. The current repeatedly reverses — it flows one way, then the other way, in a regular cycle.

Sources of a.c.:

• Mains electricity from the National Grid
• Generators at power stations

UK Mains Supply

The UK mains electricity supply is:

• Alternating current (a.c.)
• 230 V (potential difference)
• 50 Hz (frequency — the current changes direction 50 times per second, giving 50 complete cycles per second)