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Electromagnetic Induction

Inducing a current by moving a magnet

  • 3 things to know
  • Paper 2

Overview

Producing a potential difference with a bar magnet and a coil, why only a changing field induces one, moving the coil instead, and wind turbines, power stations and dynamos.

What you need to know

Answer each one before you reveal it.

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Key term

Describe how a magnet and a coil produce a potential difference, when the potential difference is induced, and how a wind turbine uses the effect.

Key term

Describe how a potential difference can be produced in the laboratory using a bar magnet and a coil of wire.

Key term

Explain why a current flows in a coil only while a magnet is being moved into it.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Describe how a potential difference can be produced in the laboratory using a bar magnet and a coil of wire.

    Model answer

    Move the magnet into or out of the coil, and a potential difference is induced across the coil while it is moving.

  2. 2

    Name the effect in which movement between a magnet and a conductor produces a potential difference.

    Model answer

    Electromagnetic induction.

  3. 3

    Explain why a current flows in a coil only while a magnet is being moved into it.

    Model answer

    A potential difference is induced only while the magnetic field passing through the coil is changing.

  4. 4

    A bar magnet is held still inside a coil connected to a sensitive meter. State the reading on the meter.

    Model answer

    The reading is zero.

  5. 5

    Describe what happens if a coil is moved over a stationary magnet rather than the magnet being moved into the coil.

    Model answer

    A potential difference is still induced, because only the relative movement of the magnet and the coil matters.

  6. 6

    Explain how a wind turbine generates electricity.

    Model answer

    The blades turn a coil and magnet past each other inside a generator, and the changing field through the coil induces a potential difference.

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