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What are permanent magnets ? Give the ways for preparing them. |
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Answer» Solution :SUBSTANCE which at room temperature RETAIN their ferromagnetic property for a long period of time are called permanent magnets. One can hold an IRON ROD in the north-south direction and hammer it repeatedly. (This method is shown in figure).  One can also hold a iron rod and stroke it with one end of a bar magnet a large number of times, always in the same sense to make a permanent magnet. An EFFICIENT way to make a permanent magnet is to place a ferromagnetic rod in a solenoid and pass a current. The magnetic field of the solenoid magnetises the rod. |
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