how does a tape recorder works?
The brown stuff on the tape is a magnetic material, let's assume it's iron powder. when you talk into the microphone, the machine sends your voice into a little transformer that the tape rubs against. This is called the recording head It sets up a magnetic field which varies with the sound and volume of your voice. As the magnetic particles riding along on the tape pass over this variable magnetic field, they are rearranged and don't change once they have left the transformer's influence. So there you have it--Magnetic particles attached to a tape which have been arranged in a recognizable pattern. When those magnetic particles pass over another transformer, (the pickup head) their magnetism induces a voltage into that coil which the machine amplifies for you to hear
1)Recording:--- the compressions and rarefactions in air affecting the diaphragm of microphone are converted by microphone into corresponding analogue electric wave . it is amplified and induces a very powerful magnetic undulations in the recording head . the unrecorded magnetic tape in the tape cassette passes at a fixed speed under the recording head . the very powerful magnetic undulations in the recording head can easily move the magnetic particles in the tape and rearrange them in a permanent way to correspond to the sound wave of the song/speech/music. 2)replaying the song/speech/music:---when the recorded tape is made to pass under the playing head at the fixed speed, corresponding electric wave is induced in the tiny wire coil which is affected by the magnetic wave pulses coming from the moving magnetic tape (on which the song/speech/music is lying recorded). this electric wave is amplified and fed to a sound box . thus the exact sound is faithfully reproduced 3)the underlying scientific principle is same as in telephone . when we speak into mouth piece of phone ,sound is converted to an analogue electric wave which travels through the telephone wires to the ear piece of the telephone at destination . there the electric signal gets converted to sound wave. but technology here is entirely different .the wave form used in tape recorder is digital and computer chips(i.e. auto control of all parameters by computer memory) and complicated electronic technology is used to control the entire process. this is all a very simple elementary explanation
