The mutual inductance `M_(12)` of coil 1 with respect to coil 2

Options

A. increases when they are brought nearer.
B. depends on the current passing through the coils.
C. increases when one of them is rotated about an axis.
D. is the same as `M_(21)` of coil 2 with respect to coil 1.

Answer

A, D

Explanation

The flux linkage between the coil increases when they are brought closer to each other, thus increasing their mutual inductance. Also, for two coils `M_(21) = M_(12) = M`, i.e. mutual inductance of both coils is same because it is defined for pair of coils.
Options (a) and (d) are correct.