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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
