Question

Find the value of x if the Mutual inductance is 20H, the inductance of coil 1 is xH and the inductance of coil 2 is 8H. The coupling coefficient is 5.

(a) 2H

(b) 4H

(c) 6H

(d) 8H

The question was posed to me during an internship interview.

My question comes from Coupling Coefficient in chapter Inductance in a DC Circuit of Basic Electrical Engineering

Answer 1

Right answer is (a) 2H

Best explanation: we know that:

k=M/sqrt(L1L2)

Substituting the values from the question, we get L1=2H.