Q1: The coefficient of coupling between two coils is 0.45. The first coil has an inductance of 75 mH and the second coil has an inductance of 105 mH. What is the mutual inductance between the coils?

ANS:C - 39.9 mH

Let coefficient of coupling b/w two coils is = K.
So, K = 0.45.

First coil inductance(L1) = 75mh.
Second " " " (L2) = 105mh.

Mutual inductance(M) = k/square root of (L1*L2).

M = 0.45*square root(75*105).

M = 39.9.