3.2
Reading: Read the text carefully.
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Today microphones are used in many applications such as telephones,
hearing aids, public events, radio and television broad casting and so on.
Although there is no question that such devices have enriched our lives
making infinitely easier, most of us have no enough idea about how these
microphones work. Let’s look at them more closely;
A microphone is an acoustic-to-electric sensor that converts sound into an
electrical signal. The cover of a microphone collects sound waves around
us. There is a diaphragm inside of the microphone. The sound waves move
it forth and back. The coil attached to diaphragm moves back and forth as
well. The permanent magnet produces a magnetic field. As the coil moves
back and forth through the magnetic field, an electric current flows
through it. The electric current flows out from the microphone to an
amplifier. The duty of an amplifier in the circuit is to increase the level of
sound.
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