Same as problem `4` except the coil `A` is made to rotate about a vertical axis in the plane of the coil (Figure). No currents flows in `B` if `A` is at rest. The current in coil `A`, when the current in `B` (at `t = 0`) is counterclockwise and the coil `A` is as shown at this instant, `t = 0`, is

Options

A. constant current clockwise.
B. varying current clockwise.
C. varying current counterclockwise.
D. constant current counterclockwise.

Answer

A

Explanation

When the current in `B` at `(t = 0)` is counter clockwise and the coil `A` is considered above to it. The counterclockwise flow of the current in `B` is equivalent to north pole of magnet and magnetic field lines are emanating upward to coil `A`.
When coil `A` start rotating at `t -0` the current in `A` is constant along clockwise along clockwise direction by Lenz's rule