There are many forms of energy. Light, sound, movement, heat, chemical energy and electrical energy are some of the most common.

Energy is never used up. It simply exists and is changed from one form to another. For example the chemicals in a battery are a store of chemical energy. When the battery is placed in a circuit and the circuit is switched on, the chemicals in the battery change and produce electrical energy. This drives a current of electricity around the circuit.

Some components in a circuit can make the energy change forms, too. For example when the current flows through a lamp some of the electrical energy is changed into light and some is changed into heat. In a buzzer some of the electrical energy is changed into sound.

A fuel is a store of chemical energy. In a power station a fuel such as coal or gas is burnt to give the heat energy needed to heat water into steam. The steam (movement energy) turns the electric generators. On the spindle of the generator is a magnet and as this spins near a coil of wire, it makes electricity flow in the wire. So in this example, the stored chemical energy of coal, gas or oil is changed into heat and then movement energy, which in turn is changed into electrical energy.

When you use the electricity in your home or school, you are using the energy stored in the fuel. In time we will run out of fuels such as coal and gas. We can make the fuels last longer by using electricity only when it is necessary. One way we can all save fuels is to switch off lights that we are not using.

We also tend to forget that food is an important source of energy. That is because we cannot easily see how energy is contained in food. But each form of food energy – sugar, starch or fat – is vital. You can even see that food has energy, because many kinds of food will burn, and some can even give out light and heat as you will see in the video of peanuts below.