Question

The figure illustrates 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. $O Q$ should be large, $O R$ should be small
• B. $O Q$ and $O R$ should both be large
• C. $O Q$ should be small and $O R$ should be large
• D. $O Q$ and $O R$ should both be small

Answer 1

Answer: (B)

In the given figure $O Q$ refers to retentivity while $O R$ refers to coercivity, for permanents both retentivity and coercivity should be high.