How do old bike lights get their power?

Question

When you pedaled, the light on your bike lit up.

How did that happen?

Answer 1

Combing the two above answers - the bike wheel spun a dynamo which is a generator. Inside the generator there is a magnet inside many coils of copper wires. The spinning action of the magnet creates a changing magnetic field which moves electrons in the wires (this is called induction). The movement of electrons is what we know as 'electricity'.

Answer 2

It was called a dynamo and consisted of a knurled spindle that was held against the (normally) front wheel and was driven by the rotation of the cycle wheel. The dynamo generated electricity - hence lights. the other option wwas batteries in each light.

Answer 3

I believe its induction from Faraday's law