Question

Electromagnets are made up of soft iron, because soft iron has
A. high susceptibility and low retentivity.
B. low susceptibility and high retentivity.
C. low susceptibility and low retentivity.
D. high susceptibility and high retentivity.

Answer 1

Hint: Electromagnets are the ones which get devoid of all its magnetism as soon as the current through it disappears. The process should be very easy to happen. So such a kind of materials are needed for the core of the electromagnets. That is why soft iron has been used.

Complete step-by-step answer:
First of all let us take a look at what susceptibility and retentivity is. Magnetic susceptibility is the amount of how much a material is magnetized when it is kept in a magnetic field. It is simply the ratio of magnetic moment per unit volume to the intensity of the magnetizing field. And also retentivity is the ability of a material to retain some amount of magnetization or magnetic property in the material itself even after the removal of the field which is induced. So in the case of soft iron it should be having low retentivity because electromagnets are the ones who get devoid of all its magnetism as soon as the current through it disappears. And also electromagnets are having high susceptibility in order to make it more powerful. Soft iron is having high susceptibility also. So it is used to make the core of the electromagnets in common. The correct answer is option A.

Note: Electromagnets are very much different from permanent magnets.it is a kind of magnet produced during the passage of current through the coils of wire while the moving charges are producing magnetic fields too.