Physics GCSE: The national grid

step up transformer

increases the voltage

step down transformer

decreases the voltage

current

flows through a wire some energy is lost as heat

power stations

power stations produce electricity at 25,000 v

power lines

Electricity is sent through these at 400,000v

household voltage

the voltage of household electricity is about 230v

What is the national grid?

The national grid is a system of wires and cables used to send electricity from power stations to homes, schools, and factories.

What happens to the current if the voltage of the electricity passing through a wire is increased?

If the voltage of the electricity passing through a wire is increased, the current is decreased.

Why does the efficiency of the electricity in a wire increase if the current is low?

The efficiency of the electricity increases if its current is low because less energy is transferred to the surroundings by heating.

What voltage of electricity do most power stations produce?

Power stations produce electricity with a voltage of 25kV.

What do transformers at power stations do?

Transformers at power stations change the voltage of the electricity from 25kV to 400kV.

What happens to the voltage of the electricity before it is sent to homes, schools, and factories?

The voltage of the electricity is reduced by transformers before being sent to homes, schools, and factories.

What is a step-up transformer?

A step-up transformer is a transformer that increases the voltage and decreases the current of electricity at the same time.

What is a step-down transformer?

A step-down transformer is a transformer that decreases the voltage and increases the current of the electricity at the same time.

What is the frequency of UK mains electricity?

50 Hz