A 10 Ω , 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 μ s . The average e.m.f. induced in the coil is

Question

A 10 Ω , 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 μ s . The average e.m.f. induced in the coil is _____ V .

TestHub · Accepted Answer

The initial current in the coil will be, i = V R = 20 10 = 2 A . Average e.m.f. developed in the coil will be, ε = - ∆ ϕ ∆ t = 0 - L i t = 20 × 10 - 3 × 2 100 × 10 - 6 = 400 V .

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