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The Challenge: Make a radio from a saucepan

Radio waves fill the space around us every second of the day. They emanate from local radio stations, mobile phones, short-wave radio transmitters around the world, and some even from satellites 36,000km (about 22,000 miles) out in space.

Radio is fundamentally about electricity and magnetism. Every time an electric current is turned on or off it creates electricity and magnetism in the form of radio waves. That's why you often hear a click on the radio when a nearby light switch is turned on or off. The radio waves radiate from the switch much like the ripples formed when a stone is dropped into a pond. Radio waves, like visible light, X-rays and microwaves, are all forms of electromagnetic radiation travelling at the speed of light — an incredible 300,000,000 meters per second (186,000 miles per second)!

A radio transmitter is simply a device that continuously produces radio waves. It uses an electric circuit that causes a current to oscillate. By varying the strength of this oscillation according to, say, the loudness of a piece of music, you can encode information about the music onto the radio waves. These encoded waves are then transmitted from an antenna and picked up by a receiver that decodes the signal so that you can hear the music again.