#P8.2a
describe the main energy sources available for use on Earth, compare the ways in which they are used and distinguish between renewable and non-renewable sources
fossil fuels, nuclear fuel, biofuel, wind, hydroelectricity, tides and the Sun
#P8.2b
explain patterns and trends in the use of energy resources
the changing use of different resources over time
#P8.2c
recall that, in the national grid, electrical power is transferred at high voltages from power stations, and then transferred at lower voltages in each locality for domestic use
#P8.2d
recall that step-up and step-down transformers are used to change the potential difference as power is transferred from power stations
#P8.2e
explain how the national grid is an efficient way to transfer energy
#P8.2f
link the potential differences and numbers of turns of a transformer to the power transfer involved; relate this to the advantages of power transmission at high voltages
#P8.2g
recall that the domestic supply in the UK is a.c. at 50 Hz and about 230 volts
#P8.2h
explain the difference between direct and alternating voltage
#P8.2i
recall the differences in function between the live, neutral and earth mains wires, and the potential differences between these wires
#P8.2j
explain that a live wire may be dangerous even when a switch in a mains circuit is open, and explain the dangers of providing any connection between the live wire and earth
the protection offered by insulation of devices