Question

Which of the following is not correct about relative magnetic permeability $\left({\mu }_r\right)$?

• A. It is a dimensionless pure ratio
• B. For vacuum medium its value is one.
• C. For ferromagnetic materials ${\mu }_r>>1$
• D. For paramagnetic materials ${\mu }_r>1$

Answer 1

Answer: (D)

For paramagnetic materials ${\mu }_r>1$

Relative magnetic permeability
${\mu }_r=\frac{\text{magnetic permeability of material}\left(\mu \right)}{\text{permeability of free space}\left({\mu }_0\right)}$

It is a dimensionless pure ratio and

for ferromagnetic materials ${\mu }_r>1$.

For paramagnetic materials ${\mu }_r<1$

Option D