What are permanent magnets ? What is an efficient way of preparing a permanent magnet ? Write two characteristic properties of materials which are required to select them for permanent magnets.

What are permanent magnets ? What is an efficient way of preparing a p

1.	What are permanent magnets ? What is an efficient way of preparing a permanent magnet ? Write two characteristic properties of materials which are required to select them for permanent magnets.
Answer» Solution :SUBSTANCES which at room temperature retain their ferromagnetic PROPERTY for a long period of time are called "permanent magenet". 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. Materials selected for PREPARING permanent magnet should have (a) high retentivity so that the magnet is a strong magnet, and (b) high coercivity so that the magnetisation is not erased by stray magnetic fields, temperature fluctuations or minor mechanical damage. (c) high permeability so that material becomes a strong magnet. Steel and alloys like Alnico, Cobalt steel and Ticonal are suitable materials for preparing permanent magnets.

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What are permanent magnets ? What is an efficient way of preparing a permanent magnet ? Write two characteristic properties of materials which are required to select them for permanent magnets.

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