magnetic recording

The recording of a signal, such as sound or computer instructions, in the form of a magnetic pattern on a magnetizable surface, such as tape or a disk coated with metal oxides. In the recording process, small electromagnets are used to convert an electrical signal into a magnetic one that magnetizes that surface. The value of the signal at any given point corresponds to the degree and polarity of magnetization of the surface at a corresponding point. During playback, the opposite process occurs, and the magnetic fields along the surface are converted into electrical signals for further processing.