Question

A circular coil expands radially in a region of magnetic field but no electromotive force is produced in the coil. It can be because
A. the magnetic field is constant
B. the magnetic field is in the same plane as the circular coil and it may or may not vary
C. the magnetic field may have a perpendicular (to the plane of the coil) component with suitably decreasing magnitude
D. there is a constant magnetic field perpendicular (to the plane of the coil) direction

Answer 1

Correct Answer - B::C
When magnetic field is in the plane of the coil, no magnetic flux is linked with the coil. Since there is no change in magnetic flux linked with coil, induced emf is zero. When magnetic field perpendicular to the plane of the coil decreases suitably and the magnetic flux linked with the coil remains constant, e = 0.