Some magnets are also made from synthetic material and are called ceramic ferrite or graphite magnets. The ceramic or ferrite magnets are manufactured from oxides of Ferric and Barium (or Strontium), with certain doping agents which differ from manufacturer to manufacturer.
Ceramic magnets are used for the purpose of :
(i) Communications —Loud speakers, microphones (bells, inductors, receivers).
(ii) Electricals —Cycle dynamos, D. C. (Small) motors, instruments, toy-motors.
(iii) Electronics —Calculators, computors, tabulators.
(iv) Transport —Car radios, aerial motors, dynamos for autos, magnetoes for motor cycles and scooters.
(v) Miscellaneous —Belts,door-latches,filters, magnetic-chucks. magnetic-games, magnetic separators, novelties, plastic materials and stationery items.
Ceramic or Ferrite magnets have the following distinct advantages :
(1) Considerable higher coercive force and retention of magnetism for a very long time.
(2) High stability to demagnetising field and temperature changes.
(3) About 60 per cent weight as compared to metallic magnets.
(4) Available at lower costs.
(5) No “keepers” necessary for long preservation.
A drawback with the ceramic or ferrite magnets, however, is that they are liable to break on falling down. Hence they should be handled with care particularly to avoid chipping of sharp edges or corners.
Magnets of all types—namely, electro or permanent, iron- alloys or ceramic—are produced by the manufacturing companies for industrial purposes. There is only one company at Bombay, Messrs Permanent Magnets Ltd. who make small Healing Magnets also. The healing magnets are in different shapes and sizes, are coloured Red, or marked N (North) and S (South) and are supplied magnetised. The other magnets supplied by this company as well as other companies for industrial purposes are supplied uncoloured, unmarked and unmag-netised unless a specific request is made for magnetisation.