The terms hard and soft magnet refer to materials that have very different magnetic properties. In general, the soft type is only magnetic for a temporary period, while hard magnets are permanently magnetic. Both are made from ferromagnetic materials and are used in the production of a wide variety of electronic goods and other everyday items.
Hard magnets rarely lose their magnetic properties. In fact, when most people talk about "magnets," they're usually referring to materials classed as hard magnets. Because they're permanently charged, hard magnets are used for many types of everyday purposes -- from colourful magnets that hang on a fridge door to the magnet that keeps the fridge door itself sealed when closed. Materials used to create hard magnets include ferrite and alnico.
Hard magnet usage
Aside from domestic application in keeping cupboard and fridge doors closed, hard magnets play a role in a number of different products. For example, everything from car motors and generators to microphones and wheel bearings contain hard magnets. More significantly, 60 per cent of all hard magnets produced are used to make disc drives and PC components, according to the University of Birmingham.
Soft magnets include materials that can be easily and quickly magnetised and demagnetised. In that sense, soft magnets are only temporarily magnetic. Because soft magnets can alternate between magnetically charged and inert in seconds, engineers use these materials in a number of different electronic devices and circuits. They're also useful in situations where a magnetic field must be turned on and off at a moment's notice. Soft magnets are made from materials such as steel and alloy nickel iron.
In electric circuits, soft magnets fall into two categories -- AC or DC. DC, or direct current, means that the soft magnet is magnetically charged during usage. For example, passing current through an electromagnet in a scrapyard allows it to become magnetic when picking up metal, then demagnetised to drop the scrap. Soft magnets also work in alternating current, or AC, circuits, such as transformers.