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Microphone.
The microphone works by producing a small induced voltage in a coil
from the effect of sound waves
hitting a diaphragm.
It is very similar to a loudspeaker in reverse
with a diaphragm instead of a
paper cone.
This type of microphone is called a
moving coil microphone.
The sound
waves strike the diaphragm and
move it
backwards and forwards at the same
frequency as the sound
(like the way the ear drum is moved inside the ear).
The moving diaphragm moves the
coil backwards and forwards
which induces
a changing current at the same frequency as the
sound.
This changing current (called the
signal) is sent to an amplifier
which makes the changing current big
enough to be used
for recording or to drive loudspeakers.
The loudspeaker reconverts
the changing current
back into the original
sound.
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