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Question
The current in a coil changes from 50A to 10A in 0.1 second. The self inductance of the coil is 20H. The induced e.m.f. in the coil is ______.
Options
800V
6000V
7000V
8000V
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Solution
The current in a coil changes from 50A to 10A in 0.1 second. The self-inductance of the coil is 20H. The induced e.m.f. in the coil is 8000V.
Explanation:
The induced e.m.f. in the coil is given by the formula:
e.m.f. = `-L(DeltaI)/(Deltat)`
Where,
L= 20H (self-inductance)
ΔI = final − Iinitial = 10A − 50A = −40A,
Δt = 0.1 s.
Substituting the values:
e.m.f. = `-20 xx (-40)/0.1 = 20 xx 400 8000 V`
The magnitude of the induced emf is 8000 V.
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