Q 12-05-064JEE MainJEE Main 2020 (7 Jan, Shift 1)Medium
Consider a circular coil of wire carrying constant current $I$, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excludes the circular coil area is given by $\phi_i$. The magnetic flux through the area of the circular coil is given by $\phi_0$. Which of the following options is correct?
Answer: (D) $\phi_i = -\phi_0$
Magnetic field lines form closed loops, so the total flux through the entire infinite plane is zero (Gauss's law for magnetism). Every line that goes up through the coil area comes back down through the rest of the plane:
$$\phi_0 + \phi_i = 0 \Rightarrow \phi_i = -\phi_0$$
Solution by Sreeraj P, M.Sc Physics