273. How does magnetism play a part in tapes to create sound?
The tape recorder first represents sound (pressure fluctuations in the air) as electric current and it then represents that current as magnetization of a tape. It magnetizes the tape to various depths to represent the different amounts of current and it uses the direction of the magnetization to represent which way the current should flow. During playback, the tape recorder measures just how deeply and in what direction the tape has been magnetized and uses that information to recreate the current and the sound.