Question

Magnetic permeability is maximum for

• A. diamagnetic substances
• B. paramagnetic substances
• C. ferromagnetic substances
• D. all of these

Answer 1

The correct option is C

ferromagnetic substances

The explanation for correct option:

1. The relationship between permeability $\mu$ and magnetic susceptibility ${\chi }_m$ is given as

$\mu ={\mu }_0\left(1+{\chi }_m\right)$

where ${\mu }_0$ is the permeability of free space.

2. For free space ${\chi }_m=0$ and $\mu ={\mu }_0$.

3. The quantity ${\mu }_r=\frac{\mu }{{\mu }_0}=1+{\chi }_m$ is called relative permeability.

Option (C):

1. For ferromagnetic substances, the magnetic susceptibility is much greater than one.
2. Therefore, their permeability is very high for such materials.

The explanation for Incorrect Option:

Option (A):

1. For diamagnetic substances, the magnetic susceptibility is less than zero.
2. Therefore, their permeability is very close to unity for such materials.

Option (B):

1. For paramagnetic substances, the magnetic susceptibility is of the order of ${10}^{-5}$.
2. Therefore, their permeability is very close to unity for such materials.

Option (D):

1. Since two options are incorrect, all of these cannot be the correct option.

Hence, the correct answer is option (C).