Electromagnets in Tape Recorders

A tape recorder is a sound recording and reproductive device that records and plays back sounds. They usually use magnetic tape for storage. It records a signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal.

Basically, an electromagnet applies a magnetic flux to the oxide on the tape. The oxide can then permanently remember the flux and play sounds back. The electromagnetic tape head itself is pretty much just a small iron loop with wire wrapped around it.