A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnetic is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains horizontal potential energy. the work required to do this comes from

Options

A. The induced electric due to the changing magnetic field
B. The current source
C. The lattice structure of the material of the rod
D. The magnetic field

Answer

B

Explanation

When current source is switched on, magnetic field sets up between poles on electromagnet.
Diamagnetic matrial, due to its tendency to move from stronger to weaker field, is thus repelled out.