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A toroid of n turns, mean radius R and c...

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 `xy-` plane. Its magnetic moment `overset(to)(m)`…..

A

is non-zero and points in the z-direction by symmetry.

B

points along the axis of the toroid `( overset(to) (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.

Text Solution

Verified by Experts

The correct Answer is:
D
Toroid has magnetic moment. The magnetic field inside the toroid is uniform. Hence, magnetic lines are circular in nature.
Magnetizing current flows in its ring on the ring surrounding the toroid ring but current I inside the toroid is zero, hence magnetic moment m = 0.
For larger distance r outside the toroid `m prop (1)/(r^3)` but it is not possible for toroid.
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