The great scientist Albert Einstein said:
Energy changers are devices that convert energy from one form to another. For example:
A car engine converts the chemical energy stored in petrol into kinetic (movement) energy. Sound and heat (thermal) energy are also produced.
We use energy changers to change energy from one form into a form that we can put to a specific use. Listed below are some examples of energy changers that we use everyday.
Kettle electrical energy into thermal (heat) energy
Torch chemical energy (in batteries) into light and thermal energy
Television electrical energy into sound and light
Loudspeaker electrical energy into sound energy
A diver gravitational potential energy into kinetic (energy) as he falls into the water
These examples all show how energy can be converted into a form that we can put to use. Even you are an energy converter!
You convert the chemical energy stored in your food into kinetic energy (to make you move), thermal energy (to keep you warm) and electrical energy (all the signals sent around your body to and from the brain are electrical signals)
Energy converters are not perfect and some of the energy they create is wasted. In the car engine example, the petrol is converted into kinetic energy, but sound and thermal energy are also produced. The sound and thermal energy are wasted energy because not all the energy contained within the petrol is being converted into kinetic energy to move the car.