A tape recorder is a machine that records sound waves into a magnetic pattern on a tape. When the pattern played back reproduces the original sound.
A person whose voice is to be recorded is asked to speak before a microphone which converts the sound into an electric current. Since this current is very weak, it is amplified by an amplifier. The current is then passed through the recording head of the tape recorder. A current passing through the coil produces a magnetic field. Since the current is alternating in nature, so it produces a varying magnetic field. During the recording, the tape moves past the recording head. The plastic tape is coated with a magnetic substance like iron oxide and so, it is called a magnetic tape. The varying magnetic field in the recording head which is in accordance to the sound produces a magnetic pattern on the tape.
This is how the sound is recorded on the tape in the form of a magnetic pattern.
The tape can be played back over and over again. To play back the tape, it is again fed past the recording head. This head now acts as the playback head. As the tape moves, its magnetic pattern causes the current to flow through the coil in the head. As the magnetic field on the tape varies, the current in the coil also varies. The current is then amplified by an amplifier and fed to a loud speaker. The loud speaker changes the current into the original sound and thus we listen to the recorded voice.
The sound recorded on a tape can be erased by an erasing head.
The recording described above is called single track recording. Nowadays two or four track recorders are available which produce stereophonic sounds.
In the last few years, cassette tape recorders have become very popular. The reel of the tape and the take-up reel are both held in a plastic case called a cassette. To record or play back, the cassette is simply placed in the record player and the correct switch is pressed.
