Question

Which of the following materials is most suitable for making an electromagnet?
A) Stainless steel
B) Silver
C) Soft iron
D) Nickel

Answer 1

Hint:A magnet which consists of a piece of some metal surrounded by a coil is termed as an electromagnet. When an electric current is allowed to pass through the coil, the metal becomes magnetic. Electromagnets will heat up very fast and energy can get lost in the form of heat. So the metal most suitable must have a low heating loss.

Complete step by step answer.

Step 1: Mention the principle on which an electromagnet operates to narrow down the most suitable metal for making electromagnets.

Electric current through a conductor will produce a magnetic field which is perpendicular to the direction of the flow of current in the conductor. An electromagnet can be considered to operate on electricity. When current is passed through an electromagnet, a magnetic field will be generated and by controlling the amount and direction of the current, we can control the amount and direction of the generated magnetic field of the electromagnet. So the flow of current causes the electromagnet to get magnetized and if the current is cut off, the magnetization ceases to exist.

A good electromagnet is supposed to have low retentivity and low coercivity. Electromagnets are known to heat up very fast and they will consume a large amount of energy. Out of the given four metals, soft iron has the least energy loss per cycle and it gets magnetised and demagnetised easily. So the most suitable material for making electromagnets is soft iron.

Hence the correct option is C.

Note:Retentivity refers to the ability of the magnetic field remaining in the material even after disconnecting the external source. Coercivity refers to the minimum value of the magnetising intensity necessary to demagnetize the material. Demagnetization refers to reversing the direction of the magnetic field generated in the material. As mentioned above, this is done by reversing the direction of the current flow.