7.2.8

Electric Motors

Test yourself

Loudspeakers

A moving-coil loudspeaker or set of headphones has an electromagnet inside a coil. A signal is passed to the loudspeaker in the form of a changing current.

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Change in current causes change in magnetic field

  • As the direction of the current changes, the direction of the magnetic field induced (brought about) in the electromagnet changes.
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Magnetic field change

  • A stationary (not moving) magnet repeatedly attracts and repels the electromagnet.
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Speakers vibrate

  • This causes the speakers to move backwards and forwards.
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Sound is created

  • This creates sound waves.

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

5.1Basics of Motion

5.2Forces

5.3Effects of Forces

5.4Pressure

6Waves

7Magnetism

8Astrophysics

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