P5 - Mains electricity
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What is DC
Direct Current - flows in one direction
What is AC?
Alternating current - repeatedly reversed direction of current
National grid?
Travel of electricity throughout the country with different energy devices
What colour is the live wire?
Red
What colour is the neutral wire?
Blue
What colour is the earth wire?
Yellow and green
What does a fuse do?
Prevents fires, is very cheap at 20p, a thin wire that melts when current exceeds its rating, 3A,5A,13A
Why do some devices not have an earth wire?
Can be connected to same material that live wire is touching to prevent electrocution, an appliance can also be double insulated with the live wire only touching the inner casing of that appliance
What is power?
Work done
What do electrons have to get past in a current?
They have to get past ions without colliding to prevent resistance and kinetic and thermal energy will be released meaning higher resistance
What is efficiency
Useful output over total input X100
What is frequency of electricity?
50Hz
What is a step-up transformer used for?
To raise voltage but keep current low to reduce resistance leading to heat loss