A toroid of n turns, mean radius R and cross-sectional radius a carries current I. It is placed on a horizontal table taken as x-y plane. Its magnetic moment `vecM`

Options

A. It is non-zero and points in the z-direction by symmetry
B. points along the axis of the toroid (m=m`phi`)
C. is zero, otherwise there would be a field falling as `(1)/(r^(3))` at large distances outside the toroid
D. is pointing radially outwards.

Answer

C

Explanation

In case of toroid, the magnetic field is only confined inside the body of toroid in the form of concentric magnetic lines of force and there is no magnetic held outside the moment of toroid is zero.
is not possible here.