Q. Compute the mutual inductance between two coils when a current of 4 a changing to 8 a in 0.5 s in one coil induces an emf of 50 mV in the other coil.
Induce emf e = - M dI/dt
M = - e / (dI/dt)
M = - (50 X 10 -3)/ (8 - 4)/0.5
= - 6.25 × 10-3 H = -6.25 mH.