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At any instant t current I through a coi...

At any instant t current I through a coil of self inductance 2 mH is given by `i=t^(2)e^(-t)`. The induced e.m.f. will be zero at time

A

1 sec

B

2 sec

C

3 sec

D

4 sec

Text Solution

Verified by Experts

The correct Answer is:
B
Induced emf = `-L(dl)/dt`
= `-L(d(t^(2)e^(-t)))/dt`
= `-L{2te^(-t)+t^(2)(-1)e^(-t)}`
= `-L{2te^(-t)-t^(2)e^(-t)}`
So, for induced emf to be zero
`e^(-t)t(2-t)=0`
`t=oo,t=2sec` (emf is zero).
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