The amount of energy in a system can be changed. It cannot be created or destroyed but it can be transferred, dissipated or stored in different ways.

Energy efficiency measures the proportion of energy which is wasted. The rate at which energy is wasted needs to be reduced and there are a number of ways to save energy, especially thermal energy.

Every person, animal and device transfers energy. Much of the energy that is supplied by electricity must be generated from other energy stores - some are renewable but most are non-renewable.

Understanding how to approach exam questions helps to boost exam performance. Questions will include multiple choice, structured, using mathematical skills and extended writing.