Question

A circular coil, carrying a constant current $i$ is kept in the $x-y$ plane. The magnetic flux through the entire $x-y$ plane excluding the area of the circular coil is given by $\phi$ and the magnetic flux through the area of the circular coil area is given by $\phi_{0}$ , then

• A. $\phi>-\phi_{0}$
• B. $\phi < \phi_{0}$
• C. $\phi=-\phi_{0}$
• D. $\phi=\phi_{0}$

Answer 1

Answer: (C)

As magnetic field lines always form a closed loop, hence every magnetic field line creating magnetic flux in the inner region must be passing through the outer region. So the magnetic flux for one of the regions will be positive and for the other, it will be negative but both will have the same magnitude. This means $\phi=-\phi_{0}$