The principle of magnetism, which explains the attractive forces between objects within magnetic fields, is central to physics and engineering. Electromagnets feature temporary magnetic fields created by electricity, while naturally magnetic materials can serve as clasps or closures. Magnets, in all their various forms, are a major part of the tools and devices you use every day, including household appliances.
Some of the easiest magnetics to identify in household appliances take the form of magnetic latches. These latches, which appear on refrigerators, freezers and some laptop computers, allow devices to close and open easily without a physical latch. Magnetic latches can form strong, even seals, which make them ideal for keeping an insulated freezer door closed or ensuring that a refrigerator door seals without the need to slam the door. Laptop latches make sure computers close tightly to protect their delicate screens, and the lack of a physical latch allows manufacturers to minimise the size of the enclosure and also eliminate an opportunity for mechanical failure.
Simple electric motors use magnets to turn electrical energy into motion. They rely on the principle of magnetic induction to generate torque, or turning power, by sending a series of alternating currents through coiled wire wound around a magnetic core. These electric motors that rely on magnets for their ability to produce motion, are inside many household appliances including blenders, mixers, power drills and screwdrivers. Electromagnets also produce the motion of speaker elements in a stereo system or television.
Household appliances also use magnets in devices that record data using an analogue or digital magnetic process, which includes devices such as VCRs or cassette tape players and recorders. These devices use magnetic heads to magnetise portions of a tape or to detect the magnetism already on the tape to play back video or audio content. Digital magnetic recording involves hard drives, which consist of magnetic layers and read-write heads that also use magnets. Digital magnetic recording is present in any device that includes a hard drive, including personal computers, external hard drives, digital video recorders and some older digital music players.