Electricity in the home

What is the frequency and voltage of mains electricity in the UK?

50 Hz and 230 V.

What is the difference between alternating current (AC) and direct current (DC)?

AC changes direction periodically, while DC flows in one direction only.

Why is AC used in mains electricity?

AC is more efficient for transmitting power over long distances.

What are the three wires in a UK plug, and their functions?

Live wire (brown) carries current to the appliance, neutral wire (blue) completes the circuit, and earth wire (green/yellow) prevents electric shocks.

What is the potential difference of the live wire relative to the earth?

230 V.

What is the role of a fuse in a plug?

The fuse melts if the current is too high, breaking the circuit and preventing damage.

Why is the earth wire important?

It provides a path for current to flow safely to the ground if a fault occurs.

What is the purpose of a circuit breaker?

It automatically switches off the current in case of a fault, providing faster and reusable protection than fuses.

What is double insulation, and why is it used?

Double insulation ensures no metal parts are exposed, removing the need for an earth wire.

What is the danger of touching the live wire?

It can cause an electric shock due to the high voltage relative to the earth.

How does the length of a cable affect safety?

Longer cables can overheat and increase resistance.

Why is copper commonly used in household wiring?

Copper has low resistance and high conductivity.

What does a residual current device (RCD) do?

It cuts off the power supply when it detects a difference between live and neutral currents.

Why is the neutral wire at 0 V?

It is connected to the earth at the power station to complete the circuit safely.

How do plugs ensure safety during disconnection?

The design ensures the live pin disconnects last, preventing live circuits from being exposed.