Household electricity Flashcards
What does DC stand for?
Direct current.
What does AC stand for?
Alternating current.
What are electrical circuits, cables, plugs and appliances designed to reduce?
The chances of receiving an electric shock.
What is a direct current?
If the current flows in only one direction it is called direct current (DC). Batteries and cells supply DC electricity.
What is a alternating current?
If the current constantly changes direction, it is called alternating current (AC). Mains electricity is an AC supply, with the UK mains supply being about 230 V. It has a frequency of 50 Hz (50 hertz), which means it changes direction, and back again, 50 times a second.
What does a cable contain?
A mains electricity cable contains two or three inner wires. Each has a core of copper. The outer layers are flexible plastic.
Why are copper and flexible plastic used in cables?
Copper, because it is a good conductor and plastic because it is a good electrical insulator.
What are the inner wires in a cable colour coded as?
Blue - neutral
Brown - live
Green and yellow stripes - earth
What are the features of a plug?
The case is made from tough plastic or rubber, because these materials are good electrical insulators.
The three pins are made from brass, which is a good conductor of electricity.
There is a fuse between the live terminal and the live pin.
The fuse breaks the circuit if too much current flows.
The cable is secured in the plug by a cable grip. This should grip the cable itself, and not the individual wires inside it.
Where does each wire go in a plug?
The blue neutral wire goes to the left, the brown live wire to the right and the green and yellow striped earth wire is on top. The fuse fits next to the live wire.
What do fuses do?
Protect electrical circuits and appliances.
It breaks the circuit if a fault occurs in the appliance and causes too much current flow.
What does residual current circuit breakers do?
They protect some circuits. They detect a difference in the current between the live and neutral wires. RCCBs work much faster than fuses do.
