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A pair of coils, each having N turns, has mutual inductance M henry. If the current in one coil changes from 1 ampere to zero in time t seconds, what is the induced emf per turn in the other coil, in volts?

1. MI/t
2. NMI/t
3. MN/t
4. MI/Nt

Correct answer: MI/Nt

Solution

Total induced emf in the other coil is M*dI/dt = M*I/t. The emf per turn is this divided by N: M*I/(N*t).

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