scince household energy

What is the equation for electrical power?

Power = Voltage × Current (P = V × I)

What is power measured in?

Watts (W)

What is the purpose of a fuse?

To break the circuit if the current becomes too large

What happens if a fuse rating is too high?

The fuse may not blow, causing overheating or fire

What happens if a fuse rating is too low?

It will blow unnecessarily and stop the appliance working

What unit is used to measure the cost of electricity?

Kilowatt-hour (kWh)

What does one kilowatt-hour mean?

Using 1 kW of power for 1 hour

What is the equation for electrical energy?

Energy (kWh) = Power (kW) × Time (hours)

How is the cost of electricity calculated?

Energy used (kWh) × cost per kWh

What is the UK mains voltage?

About 240 V

What type of current is mains electricity?

Alternating current (AC)

What are the three wires in a plug?

Live, Neutral, Earth

What colour is the live wire and what does it do?

Brown – carries current to the appliance

What colour is the neutral wire and what does it do?

Blue – completes the circuit (0 V)

What colour is the earth wire and what does it do?

Green/yellow – safety wire

Which wire is connected to the fuse?

Live wire

How does the earth wire protect the user?

Provides a low-resistance path to earth

Why does the fuse blow in a fault?

A large current flows and melts the fuse

What is double insulation?

Two layers of insulation between live parts and the user

Do double-insulated appliances need an earth wire?

No

What symbol shows double insulation?

A square inside another square

What does the cable grip do?

Prevents wires being pulled out of the plug