A metal ring is placed in a magnetic field, with its plane `_|_` to the field. If the magnitude of the field begins to change, the ring will experience

Options

A. a net force
B. a torque about it axis
C. a torque about a diameter
D. a tension along its length

Answer

D

Explanation

When the field changes, a current flow along the ring, each section of the ring now experience an ampere force acting either outward or inward. The ring will tend to expand or contract, and hence experience a tension along its length.