Mains electricity Flashcards
what is direct current?
it only flows in one direction
what does direct current look like on a voltage-time graph?
a straight horizontal line at a constant pd
what are some sources of direct current?
- car batteries
- dry cells
- solar cells
what is alternating current?
it constantly changes direction
what would alternating current look like on a voltage-time graph?
a curve alternating between positive and negative voltages (the direction of flow)
what is the frequency and voltage of UK mains electricity?
- frequency: 50Hz
- voltage: 230V
what are the 3 coloured wires in 3-pin plugs/3-core cables?
- brown: live wire
- blue: neutral
- green and yellow stripey: earth
what are the wires made out of?
copper - it s a good conductor
what are the parts of a plug?
- outer insulation - safety
- cable grip - holds wires in place
- live wire - where current enters the device
- fuse - glass or ceramic canister with thin wire that melts if it gets too hot because of a fault
- neutral wire - completes the circuit with the live wire
- earth wire - provides a path for current to flow from the case of the device to the ground if there is a fault
what is the live wire’s and the neutral wire’s voltage?
- live wire = 230V
- neutral wire = 0V
why is the earth wire important?
without it, if there is a fault and the live wire becomes loose, there is a danger it could touch the case. The next person who touches it could get electrocuted
what does the earth wire do if there is a fault?
