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How Does a Bicycle Generator Work?

A bicycle generatoruses human power to generate electricity…

A bicycle generatoruses human power to generate electricity…

But how?

Conservation of Energy

Since energy is conserved, the chemical energy in the person’s body is converted into mechanical energy in the bicycle, then electrical energy in the motor.

Motor

Ampere's law states that an electric charge passing through a looped circuit produces a magnetic field.

Interaction of the internal electromagnet with a surrounding fixed magnet produces the attractive and repulsive force associated with the poles of magnets and causes rotation.

Armature

PermanentMagnets

Motor

A motor uses electrical energy to create rotational motion, but the bicycle generator uses mechanical energy and converts it into electrical energy.

The motor can act as a generator if the person’s pedaling overcomes the electromotive force of the battery.

Diode

A diode allows current to flow in only one direction (from anode to cathode). Without it, the motor would cause the tire to spin instead of the other way around.

Anode Cathode

Generator

Michael Faraday discovered that if an object or material that conducts electricity passes through a magnetic field, then an electric current will begin to flow through that material.

In other words, the spinning tire causes the motor shaft to rotate, which produces a current through the leads.

Shaft

Leads

Battery

The electricity generated could be used to charge a battery and be stored, or could be used directly to power appliances.

Inverter

But there are two types of electric current: direct current (DC) and alternating current (AC).

So we can’t connect appliances directly to the generator unless we use an inverter.

Inverter

A car battery provides direct current for all the electrical components.

Our homes, on the other hand, are powered by alternating current electricity.

Once the setup is complete, it can be used to power low-wattage household appliances, like charging a cell phone.

For a challenge, try making a “human-powered” smoothie!

Sources

Nicholson, Joseph. "How Does an Electric Motor Work?." ehow.com. Web. 14 June 2010. <http://www.ehow.com/how_4569196_electric-motor-work.html>.

Orwell, Mark. "How Do Electric Generators Work?." ehow.com. Web. 14 June 2010. <http://www.ehow.com/how-does_4564423_electric-generators-work.html>.

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