2- Mains Electricity Flashcards
What is the 1)frequency 2)voltage of the mains supply in the UK?
1) 50hertz (changes direction 50times a second
2) 230 volts
What is an alternating current? (Ac)
The current from the mains supply passes in one direction, then reverses and passes in the other
What is the live wire?
The wire of a mains circuit with potential that alternates from positive to negative and back, each cycle (with respect to the neutral wire)
What is the neutral wire?
The wire of a mains circuit’s potential is close to zero volts
What is the peak voltages of the live wire?
+325V and -325V
How are electrical appliances connected to the mains supply?
Through the sockets, using cables and three pin plugs
Why is the outer cover of a plug made of plastic or rubber?
They are good electrical insulators
Why are the pins on the plug made of brass?
They are good electrical conductors. It is also hard and will not rust or oxidise
Where is the earth wire connected on a three pin plug?
The longest pin
What is each wire connected too in the plug?
Earth Green and Yellow wire- earth pin
Neutral Blue wire- neutral pin (left)
Live Brown wire- live pin (right)
Why must appliances with metal cables be earthed?
The case is attached to the earth wire
What are the safety aspects to a plug?
Insulating plastic cover and cable
Cable pin
Fuse
How does a fuse work?
If a fault develops in the appliance, the wire inside the fuse box melts and breaks the circuit
What should the rating of a fuse be?
Slightly above the normal working current of the appliance so it melts in time
What can be used instead of a fuse and how does it work?
A circuit breaker - an electromagnet switch that opens and breaks the circuit if the current is too big
