Question

During a 59-ms interval, a change in the current in a primary coil occurs. This change leads to the appearance of a 7.4-mAcurrent in a nearby secondary coil. The secondary coil is part of a circuit in which the resistance is 12 Ω. The mutual inductance between the two coils is 3.2 mH. What is the change in the primary current?
ΔI_p =   ---Select--- Wb V A T GO Tutorial

Additional Materials

Section 22.8

Answer 1

The e.m.f. induced in the secondary Vs = M dI / dt
Also in the secondary circuit Vs = R Is

R = 12 ohms
Is = 7.4 x10^-3 A
dt = 59x10^-3 s
M = 3.2 x10^-3 H

Vs = 12 x 7.4 x10^-3 = 88.8 x10^-3 Volts
The change in the primary current dI is given by ,
dI = Vs dt / M = 88.8 x10^-3 x59 x10^-3 / 3.2 x10^-3 = 1.637 A