Name: Direct and Alternating Current
Uploaded: 2019-07-19
Duration: 9 min 33 s
Description: The basics of alternating and direct current are discussed in detail with the process of their generation and transmission. The video points out the advantag...

Question

Differentiate between an electromagnet and a permanent magnet.

Accepted Answer

Electromagnet Permanent magnet

It is a temporary magnet. It behaves like a magnet only until the current flow in the solenoid.

It is a permanent magnet. It does not lose its magnetism easily. To demagnetize it, one needs to heat it or throw it repeatedly on the floor from some height.

It can produce a very strong magnetic field. It produces a weak magnetic field.

The strength of the magnetic field produced by it can be increased or decreased by increasing or decreasing the number of turns in the solenoid or the magnitude of the current. The strength of the magnetic field produced by a permanent magnet cannot be changed.

Its polarity (north and south poles) can be reversed by reversing the direction of current through the solenoid. Its polarity cannot be changed.

It is usually made of soft iron. It is usually made of alloys like carbon steel, cobalt steel, tungsten steel, chromium steel, alnico (an alloy of aluminium, nickel, cobalt and iron)

They are used in cranes to lift heavy scrap iron; also used in motors, generators, relays, loudspeakers, MRI machines, Maglev trains, etc.
Strong permanent magnets made of alloys are used in microphones, electric clocks, voltmeters, ammeters, loudspeakers, etc.

Differentiate between an electromagnet and a permanent magnet.

Important Questions on Magnetic Effects of Electric Current

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