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 m
(a) is non-zero and points in the z-direction by symmetry.
(b) points along the axis of the tortoid (m = mφ ).
(c) is zero, otherwise there would be a field falling as 1/r3 at large distances outside the toroid.
(d) is pointing radially outwards.
