Question related to a bicycle dynamo and a wheel.

Why a current flows through the bicycle lamp when the wheel of the bicycle turns?

The wheel turns a generator that produces a voltage. The voltahe lights uop the bulb.

Generator-run bike headlights are less commonly used these days. The higher efficiency of LED headlamps with alkaline or lithium ion batteries makes them a better choice; the lamps are smaller, and need no generator. I have not had to replace my LED light batteries for two years. The wheel drag resistance due to the generator also slows down the bike a lot. It is like pedaling with the brakes on.

When the wheel of a bicycle turns, a current flows through the bicycle lamp due to the presence of a bicycle dynamo. A bicycle dynamo is a device that generates electricity by harnessing the mechanical energy from the rotation of the bicycle wheel.

Now, let me explain the process in more detail. Inside the dynamo, there are magnets and coils of wire. As the bicycle wheel spins, it rotates a small magnet located within the dynamo. This, in turn, induces an electromotive force (EMF) in the wire coils.

According to Faraday's law of electromagnetic induction, when a conductor (wire) cuts through magnetic field lines or experiences a changing magnetic field, it induces a current in the conductor. In the case of a bicycle dynamo, the rotating magnet creates a changing magnetic field as it rotates near the wire coils. This changing magnetic field induces an electric current in the wire.

The induced current flows through the wire connected to the bicycle lamp, completing the circuit and causing the lamp to light up. Essentially, the rotation of the bicycle wheel generates mechanical energy, which is converted into electrical energy by the bicycle dynamo, ultimately powering the lamp.

Therefore, when the wheel of the bicycle turns, it causes the magnet inside the dynamo to rotate, creating a changing magnetic field that induces a current in the wire coils, leading to the flow of electricity through the bicycle lamp.