Magnitude of the change in the primary current??

Question

During a 56 ms interval, a change in the current in a primary coil occurs. This change leads to the appearance of a 6.0 mA current in a nearby secondary coil. The secondary coil is part of a circuit in which the resistance is 12 . The mutual inductance between the two coils is 4.1 mH. What is the magnitude of the change in the primary current?

Answer 1

The EMF in the second coil is created by the change in the current from the first coil

the EMF in the second coil is 6E-3*12=72 mV

72E-3=di/dt*m

so the change in the current is

72E-3/4.1E-3*56E-3=983.4 mA