Question

For magnetically coupled circuits, mutual inductance is always _______.
1. infinite
2. negative
3. positive
4. zero

Answer 1

Correct Answer - Option 3 : positive

Concept:

Mutual inductance (M) between two coupled coils is given by

\(M = k\sqrt {{L_1}{L_2}} \)

Where,

L1 and L2 are self-inductance of the two coils

k is the linking coefficient of the two coils

Explanation:

For two coupled coils, K ≤ 1

If K = 1, it is said to be tight coupling i.e, ideal.

If K < 1, it is said to be loosely coupled

Therefore, for magnetically coupled circuits mutual inductance is always positive.