How does a radio work?

A radio pulls one voice out of an invisible sea of waves, using a coil, a capacitor and a diode. A classic transistor radio is a ferrite rod antenna, a gang tuning capacitor, IF transformer cans, six or seven transistors, a detector diode, a speaker and four D cells (6 V).

Read how it works: How does a radio work? · The history of radio · More boxes on Glassbox

Chapters in this interactive model

1. Inside a transistor radio: A ferrite rod, a tuning capacitor, a few transistors, a speaker and four big batteries.
2. Radio waves: invisible light: Shake a charge and ripples of electric and magnetic field race away at the speed of light.
3. Riding a wave: AM and FM: A voice cannot fly on its own. It hitches a ride on a fast carrier wave, by changing its size or its frequency.
4. Tuning: a circuit that rings: A coil and a capacitor pass one frequency and turn the rest away.
5. The superheterodyne receiver: Shift every station to one fixed frequency, then filter and amplify it there.
6. Radio in India: From Akashvani in every home to cyclone warnings at sea, ham operators and village stations.