Magnetic Tape:

Recording tape is the material you find in cassette players. Nowadays, magnetic tape is mostly obsolete, though it is still sometimes used for home entertainment, specially high fidelity (hi-fi) music and home video. It can also be found in several high-capacity computer data storage systems.

The tape consists of millions of particles of iron oxide close attach to a plastic or non-ferromagnetic metal strip. A fluctuating magnetic field, generated by the recording head, polarizes such particles. As the field changes in strength next to the recording head, the tape passes by at a constant, controlled speed. This generates areas in which the iron oxide particles are polarized in either direction. Whenever the tape is run at similar speed through the recorder in the play-back mode, the magnetic fields about the individual particles cause a fluctuating field which is detected by a pickup head. This field has the similar pattern of variations as the original field from the recording head.

Magnetic tape is available in different widths and thicknesses for different applications. Thick-tape cassettes do not play as long as thin-tape ones, though the thicker tape is more resistant to stretching. The speed of the tape establishes the fidelity of the recording. Higher speeds are favored for music and video and lower speeds for voice. The data on a magnetic tape can be erased or distorted by external magnetic fields. And hence, tapes must be protected from such fields. Keep magnetic tape away from permanent magnets or electromagnets. The extreme heat also can damage the data on magnetic tape, and when the temperature is high sufficient, physical damage takes place as well.