As you watch a television programme, vision and sound are reaching your receiver by means of radio waves travellingar the speed of light. In the television studio, cameras convert light into electric currents and microphones do the same with sound. These currents are amplified, converted to electromagnetic waves and transmitted through an aerial. They pass through the atmosphere to the aerial of your receiver. In the receiver, they are changed back to electric currents which are used to recreate vision and sound. This book explains how these processes are carried out.