Electromagnetic Induction and Generators Flashcards

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What is electromagnetic induction?

It is making a potential difference in a wire when the magnetic field through it changes. If the circuit is complete, a current flows.

What two actions can cause induction in a coil?

Move a magnet into or out of the coil, or move or rotate the coil in a magnetic field.

What must be true for an induced current to flow?

The wire or coil must be part of a complete circuit.

How can you make the induced potential difference bigger?

Move faster, use a stronger magnet, or use more turns on the coil.

What happens to the induced current if you reverse the movement or the magnetic field?

The direction of the current reverses.

What does Lenz’s law say about the induced current?

It opposes the change that made it.

Why do you feel a resisting force when induction happens?

The induced field opposes the motion, so you must do work to keep moving.

What is an alternator?

A generator that makes alternating current (AC) by rotating a coil with slip rings.

What is a dynamo?

A generator that makes direct current (DC) using a split-ring commutator.

What does a split-ring commutator do in a dynamo?

It swaps the connections each half turn to keep the current in one direction.

What happens to an alternator’s output when you spin it faster?

The potential difference gets bigger and the frequency increases.

What is the induced potential difference when nothing is moving or changing?

Zero, because there is no change in the magnetic field.