# Magnetism: The Generator Effect

## The Generator Effect

• The generator effect is the production of electrical voltage or potential difference because of the relative motion between a conductor and a magnetic field. This is the opposite of the motor effect.

• According to Faraday’s Law of Electromagnetic Induction, the magnitude of the induced voltage is directly proportional to the rate of change of the magnetic field with respect to time.

• The direction of the induced current is always such that it will oppose the change in magnetic field that produced it, as stated by Lenz’s Law.

• The direction of the induced current can be determined using Fleming’s right-hand rule: the thumb represents the direction of motion, the first finger represents the field, and the second finger represents the induced current.

• The magnitude of the induced voltage can be increased by moving the conductor faster, using a stronger magnetic field, or increasing the length of the conductor in the magnetic field.

## Applying the Generator Effect

• Generators use the generator effect to convert mechanical energy into electrical energy. This is done by rotating a coil of wire (the armature) in a magnetic field.

• In a generator, the armature is connected to the output terminals of the generator to transfer the induced current.

• The direction of the induced current alternates every half-turn, producing an alternating current (AC). This is in contrast to a motor, where a commutator is used to produce a direct current (DC).

## Practical Applications of the Generator Effect

• Dynamo torches (hand-cranked torches) use a small generator to produce electricity. When you crank the handle, you create mechanical energy, which the generator converts into electrical energy to power the light bulb.

• Large scale generators in power stations work using the same generator effect. These are usually driven by steam turbines rotated by heat energy from burning fossil fuels or nuclear reactions.

• The generator effect is also used to create electricity in wind turbines. The wind rotates the blades of the turbine, which drives a generator to produce electricity.

• In computer hard drives, the generator effect is used to detect the binary data on the hard drive platter. The data is stored in tiny magnetised areas. When they pass under the read head, they induce a small current, signalling a binary 1.