Electricity in the home

What are the 2 different ways electric current can flow?

• Direct current- batteries

• Alternate current- mains electricity

What is the frequency and potential difference of the mains electricity supply in the UK?

• 50Hz

• 230V

What colour is the: neutral, earth, and live wire?

Neutral- blue

Earth- Green and yellow

Live- brown

What does the neutral wire do?

It completes the circuit and carries electricity back to the power source

What does the earth wire do?

Provides a path for current to flow from the case to the ground if there is a fault

What does the live wire do?

Carries the current to the appliance

What is earthing?

If the live wire comes loose, it could touch the case and electrocute the next person who uses it

↳ The earth wire is connected to the case and attached to the ground so current can pass through the case and into the ground

What does a fuse do?

It contains a small wire which can gets hot if too much current passes through it, causing it to melt and break the circuit so the case of the device is no longer live

Explain why transformer x is used in the national grid (4)

Transformer x is a step-up transformer

Which increases potential difference and decreases current

So less heat energy is lost to the cables

Therefore increasing efficiency

Explain why transformer y is used in the national grid

Transformer y is a step down transformer which

decreases potential difference and increases current

so that it is safe for the consumer

What determines if a transformer will step up or step down the voltage?

The number of coils

↳ Step-down transformers → more turns on the primary coil than the secondary

What are transformers used for?

To change voltages and currents

↳ since power transferred must stay the same:

• increasing voltage decreases current

• decreasing voltage increases current