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.

A toroid of n turns, mean radius R and cross-sectional radius a carrie

1.	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.
Answer» (c) is zero, otherwise there would be a field falling as 1/r³ at large distances outside the toroid.