Page 49 - Curriculum Visions Dynamic Book

Ferrites that retain their magnetism after being magnetized are called “hard ferrites.” Hard ferrites are used as permanent magnets. Their uses include magnetic inserts in refrigerator door seals, in microphones and loudspeakers, in motors, especially cordless varieties, and also in cars.
Ferrites that do not retain their magnetism are called “soft ferrites.” They are commonly used in electrical transformers. One place where they are found in this role is around the necks of cathode ray tubes (television screens), where they help form the picture on the screen.
Magnetic ceramics are also widely used to provide permanent storage of information in computers. All magnetic tapes, whether for video, audio, or computer data, are plastic coated with ferrites. They can be seen in the brown coating on the tape. Hard disks and floppy disks similarly have coatings of ferrite. The ferrites can be magnetized by passing over magnetic read and
write heads. More often than not, these heads are also made from ferrite.
Paint containing ferrites can coat military aircraft and make them “invisible” to radar. This
(Below) Iron oxide powder is stuck to a plastic tape and used as a cassette for audio and video recording and playback.
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