Question

The figure illustrate how B, the flux density inside a sample of unmagnetised ferromagnetic material varies with $B_0$, the magnetic flux density in which the sample is kept. For the sample to be suitable for making a permanent magnet

• A. OQ should be large, OR should be small
• B. OQ and OR should both be large
• C. OQ should be small and OR should be large
• D. OQ and OR should both be small

Answer 1

The correct option is B OQ and OR should both be large

In the given figure OQ refers to retentivity while OR refers to corecivity, for permanents both retentivity and corecivity should be high.