Question

Which of the following is a property of a hard magnetic material?

(a) Low hysteresis

(b) Low eddy loss

(c) Low coercive force

(d) High residual induction

The question was posed to me by my college professor while I was bunking the class.

I want to ask this question from Soft and Hard Magnetic Materials in chapter Magnetic & Insulating Materials of Engineering Material & Metallurgy

Answer 1

The correct answer is:

(d) High residual induction

Explanation: A hard magnetic material is characterized by the following properties:

• High coercive force: Hard magnetic materials require a large amount of energy to demagnetize them.
• High residual induction (remanence): After being magnetized, hard magnetic materials retain a significant magnetic field (residual magnetism) even when the external magnetizing force is removed. This is why hard magnetic materials are used to make permanent magnets.
• High coercivity: It resists changes to its magnetization, making it difficult to demagnetize once it is magnetized.

In contrast:

• Low hysteresis and low eddy loss are more characteristic of soft magnetic materials, which are easily magnetized and demagnetized and have minimal energy losses when the magnetic field changes.

So, the correct answer is (d) High residual induction.