Two coils of wire are placed close together. Initially, a current of 1.80 A exists in one of the coils, but there is no current
in the other. The current is then switched off in a time of 4.02 x 10-2 s. During this time, the average emf induced in the other coil is 4.38 V. What is the mutual inductance of the two-coil system?
