Radio Speakers
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Radio speakers use permanent magnets and electromagnets. A permanent magnet provides a force of attraction or repulsion to the pulsating, polarity changing electromagnetic field produced by the pulsating current from the radio's amplifier. This pulsating current is run through a large coil of wire in the speaker called the voice coil.
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When the polarity of the magnetic field of the voice coil is the opposite polarity of the permanent magnet's field, the speaker cone is pulled backward towards the permanent magnet.
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When the polarity of the magnetic field of the voice coil is the same polarity of the permanent magnet's field, the speaker cone is pushed forward away from the permanent magnet.
The movement of the speaker's cone moves the air, the air causes our ear drum to move and our brain interprets the movement as sound.
Copyright 2008,
by the Contributing Authors.
Cite/attribute Resource.
jfrank. (2008, February 12). Radio Speakers. Retrieved November 22, 2009, from WSU Web site: http://ocw.weber.edu/automotive-technology/ausv-1320-automotive-electronics/4-magnetism/radio-speakers.
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