A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This can be because

Options

A. The magnetic field is constant
B. The magnetic field is in the smae plane as the circular coil and it may or may not vary
C. The magnetic field has a perpendicular ( to the palne of the coil) component whose magnitude is decreasing suitably
D. There is a constant magnetic fied in the perpendicular ( to the plane of the coil direction)

Answer

B,C

Explanation

When circular coil expends radially in a region of magnetic field such that the magnetic field is in the same plane as the circular coil or the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably in such a way that the cross product of magnetic field and surface area of plane of coil remain constant at envery instant.