Mains electricity Flashcards
direct current
an electric current that always flows in one direction e.g. electronic circuits in computers and stereos
alternating current
an electric current that is constantly changing direction, it’s produced by most generators and is used in mains electricity e.g. motors
what are the different parts of a plug and their colours?
-earth wire (green/yellow)
-live wire (brown)
-neutral wire (blue)
-fuse
-cable grip
-outer insulation
what’s the function of a live wire?
carries p.d. from the supply and is connected to the fuse
what’s the function of the neutral wire?
completes the circuit
what’s the function of the earth wire?
the safety wire (stops the appliance becoming live)
how do fuses work?
-a fuse contains a thin wire, which melts if the current is too high
-this breaks the circuit and so electricity is unable to flow through the appliance
-the appliance stops working and any danger has been averted
-fuses act as an early warning system, preventing appliances from being damaged by surges in electricity and warning owners of faults
what is the average voltage of the mains supply in the UK?
230 volts
what is the mains frequency?
50 Hertz
describe the oscilloscope trace for direct current
a raised line that flows in one direction
describe the oscilloscope trace for an alternating current
a wavy line that changes direction back and forth