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When a current is passed through the coil, a small magnetic field is momentarily created which realigns the iron molecules in the coating into one direction in a small region, thereby "writing" a 1 or a 0 onto the platter in that place. The coil in the read-write head can also be used to sense the presence of a magnetic field oriented in a certain direction. When a wire is moved through a magnetic field, as Faraday discovered 160 years ago, a current is generated in the wire. Thus, moving the coil of the read-write head over a magnetized region will cause a current to flow in the coil wire, which can be sensed by the electronics, making it possible for the computer to "read" the 1 or 0 that is stored on the platter in that small region. |
