the generator effect

What is the generator effect?

The generator effect is when a changing magnetic field induces a potential difference (voltage) in a conductor, which can cause a current to flow if the circuit is complete.

so if the wire stops moving there is no induced pD as there’s no longer a change in magnetic field

How can a voltage be induced in a conductor?

A voltage is induced when:

1. A wire or coil of wire moves through a magnetic field.

2. A magnet moves into or out of a coil.

3. The magnetic field around a coil changes (e.g., alternating magnetic field).

(The wire must cut through magnetic field lines.)

What increases the size of the induced voltage?

Increasing the speed of movement

• Using a stronger magnetic field

• Increasing the number of turns in the coil

• Using a longer coil of wire

How can you reverse the direction of the induced voltage?

Move the wire in the opposite direction

• Reverse the poles of the magnet

How can you determine the direction of the induced voltage?

Use Fleming’s Right-Hand Rule:

• Thumb = Motion of conductor

• First Finger = Magnetic field (North to South)

• Second Finger = Induced current (Positive to Negative)

How does an alternator generate electricity?

A coil rotates in a magnetic field.

• The changing field induces an alternating current (AC).

• A slip ring commutator allows the current to change direction every half-turn, maintaining AC output.

• carbon brushes provide a good electrical connection between the coil and the external circuit

How does a dynamo generate electricity?

A coil rotates in a magnetic field.

• A split-ring commutator ensures the current always flows in the same direction, producing DC output.

What effect does an induced current have on the magnetic field?

Lenz’s Law states that the induced current produces a magnetic field that opposes the change that caused it.

What is the energy transfer in a generator?

• Kinetic energy (movement of coil/magnet) → Electrical energy (induced current)

• Some energy is wasted as heat due to resistance in the wires.

What is a microphone?

A microphone is a device that converts sound energy into electrical energy using the generator effect.

How does a microphone convert sound into an electrical signal?

• Sound waves hit a diaphragm (thin sheet inside the microphone).

• The diaphragm vibrates with the sound waves.

• The diaphragm is attached to a coil of wire, which moves inside a magnetic field.

• The movement of the coil cuts through the magnetic field, inducing a potential difference (voltage) via the generator effect.

• The alternating voltage is sent to an amplifier, then a speaker or recording device.