Question

Two circuits have coefficient of mutual induction of 0.09 henry. Average e.m.f. induced in the secondary by a change of current from 0 to 20 ampere in 0.006 second in the primary will be(a) 120 V(b) 80 V(c) 200 V(d) 300 V

Answer 1

answer : option (d) 300V

explanation : it is given that,

coefficient of mutual induction, M = 0.09H

change in current from 0 to 20A in 0.006 second in the primary coil

so, rate of change of current with respect to time, $\frac{di}{dt}$ = 20/0.006

now, induced emf in the secondary coil = M × di/dt
= 0.09 × 20/0.006 = 300V

hence, answer is option (d)