Question

What are magnetic hard materials?

(a) High retentivity, low coercivity

(b) High retentivity, high coercivity

(c) Low retentivity, low coercivity

(d) Low retentivity, high coercivity

The question was posed to me in a job interview.

This is a very interesting question from Magnetic Materials in portion Electrical Engineering Materials of Design of Electrical Machines

Answer 1

The correct choice is (b) High retentivity, high coercivity

The explanation is: High retentivity is required for protecting the magnetic materials from losing its magnetic property. High coercivity is required to reduce the effect of retentivity to protect the material.