Difference between bar magnet(temporary magnet) and electromagnet
Bar Magnet
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The substances which at room temperature retain their ferromagnetic property for a long period of time are called permanent magnets.
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An efficientway to make a permanent magnet is to place a ferromagnetic rod in a solenoid and then pass current. The magnetic field of the solenoid magnetizes the rod.
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The material used for making permanent magnets should have high retentivity—so that the magnet is strong, and high coercivity—so that the magnetization is not erased by stray magnetic fields, temperature fluctuations or minor mechanical damage.
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Some suitable materials for making permanent magnets are alnico, cobalt steel.
Electromagnet
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The core of an electromagnet ismade of ferromagnetic materials, which have high permeability and low retentivity (ability to retain magnetism on removal of current).
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The mostsuitable material for making an electromagnet is soft iron.
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By placing a soft ironrod in a solenoid and passing current, the magnetism of the rod can be increased thousand fold.
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Electromagnets are used in electric bells, loudspeakers and telephone diaphragms. Giant electromagnets are used in cranes to lift machinery and bulk quantities of iron and steel.
Bar Magnet
-
The substances which at room temperature retain their ferromagnetic property for a long period of time are called permanent magnets.
-
An efficientway to make a permanent magnet is to place a ferromagnetic rod in a solenoid and then pass current. The magnetic field of the solenoid magnetizes the rod.
-
The material used for making permanent magnets should have high retentivity—so that the magnet is strong, and high coercivity—so that the magnetization is not erased by stray magnetic fields, temperature fluctuations or minor mechanical damage.
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Some suitable materials for making permanent magnets are alnico, cobalt steel.
Electromagnet
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The core of an electromagnet ismade of ferromagnetic materials, which have high permeability and low retentivity (ability to retain magnetism on removal of current).
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The mostsuitable material for making an electromagnet is soft iron.
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By placing a soft ironrod in a solenoid and passing current, the magnetism of the rod can be increased thousand fold.
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Electromagnets are used in electric bells, loudspeakers and telephone diaphragms. Giant electromagnets are used in cranes to lift machinery and bulk quantities of iron and steel.
