# GCSE physics ideas and context

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• Created by: Maria
• Created on: 02-05-12 09:04

1) What is the National grid?

A highvoltage electric power transmission network, generating electricity everywhere in England. England uses 240v.

2) How does a generator work?

Mains electricity is produced by generators. They induce the current by spinning a coil of wire inside a magnetic field. As this happens a potential difference in between the ends of the coil, which causes the current to flow.

3) How does a transformer work?

A transformer is an electrical device that changes the voltage of an AC(Alternating Current) supply.

• Step-up transformer - increases voltage
• Step down - decreases voltage.
• Step-downs are used for phone chargers and cd players.

Transformers cannot be used on DC ( Direct Current - batteries)

4) Transformer equations ?

The transformer equation relates the number of turns of wireto the difference in voltage between the primary and secondary coils.

Vp/Vs =