Question

A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field $B$. Then the field inside the paramagnetic substance is:

• A. more than $|\overrightarrow{B}|$ and parallel to $\overrightarrow{B}$.
• B. less than $|\overrightarrow{B}|$ and anti-parallel to $\overrightarrow{B}$.
• C. less than $|\overrightarrow{B}|$ and parallel to $\overrightarrow{B}$.
• D. Zero

Answer 1

The correct option is D Zero

Magnetic field lines do not pass through the diamagnetic sphere, as shown


Therefore, there will be no magnetic field inside the cavity of the sphere. Hence, the paramagnetic substance kept inside the cavity will experience no force.

So, option $\left(D\right)$ is correct.