This is a really important topic – you need to be able to understand the ideas of electrical current, potential difference (voltage) and resistance, and answer questions on how they behave in series and parallel circuits. But you have no chance in an exam if you are asked a question about a thermistor or a diode and can’t remember what they do or recognise their circuit symbol.
The good news is that none of it is particularly complicated – in fact, most of it is stuff you learned in Key Stage 3.
BBC Bitesize revision for this topic is in two parts – click here and also click here.