A radio, like any other electrical appliance, draws electricity for power. In a wind-up radio, this electricity is converted from the mechanical energy of a winding mechanism, which is basically a very small electric generator.
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The Power Used By A Radio
The Electricity Generation in a Wind-Up Radio
Most electric generators require spinning rotors to generate electricity. The spinning of this rotor is generated by the winding motion of your hands. As the rotor, which is made of copper, turns inside the radio, it is turning inside a magnetic field. This spinning of the rotor inside the fixed magnetic field generates electricity in accordance with Faraday's Law of Induction. The electricity generated by this spinning rotor can be sent from the winding mechanism to the components of the radio by brushes attached to an electrical load.
The Final Working of the Radio
The electricity generated by the winding motion of the rotor is used by the circuitry of the radio. This spreads the electricity to the necessary components in the radio, allowing the radio to pick up a signal and emit sound through a speaker.