To throw light on the matter ... and is responsible for the “gear change” sound of many electric trains. We’re particularly taken by the sound of some German and Austrian locomotives ...

This electrical energy is transferred to your home where it powers your bedside lamp, your toaster and your TV. The light and sound from your TV are examples of useful energy but your telly also ...

An animated sequence that illustrates a range of different light sources. The Sun, fire, electric lights and torches are all shown. Darkness is presented as the absence of light and shadows as ...