7.11 Electricity in the home Flashcards
What is the difference between AC and DC
AC = alternating current
Current produced by alternating voltages where the positive and negative ends of the p.d. keep switching
DC = direct current
Current only moves in one direction. The positive and negative ends of the source are fixed
What type of current is used in UK mains supply?
AC at 230 volts. The frequency is 50 hertz (Hz) - i.e. the alternating happens in 50 cycles per second
What is a three core cable? What do the difference wires represent?
Three wires, each having a plastic coating
Brown = live wire (230 V)
Blue = neutral wire (0 V)
Green and yellow = earth wire (0 V)
Current flows through brown and blue wires
Earth wire is for safety - it stps the appliance casing from becoming live
Which wire should a fuse be connected to?
Live wire - so if there is too much current flowing through the live wire, the circuit can be shut off.
Same for switches.
How are fuses rated?
According to a maximum current that it will allow through before breaking
E.g. 3 Amp, 5 Amp, 10 Amp
The higher the rating of a fuse, the thicker the wire within it.
Why are connections between live and earth wires dangerous?
This creates a low resistance parth to earth, so a huge current will flow, which can result in a fire
What is a circuit breaker
These cut of electricity supply (e.,g. to a house) if there is a current surge.
Better than fuses as they turn off quicker, and they don’t need to be replaced (like a broken fuse does)
