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What will be the value of i (t) for t > 0, the circuit shown in figure?
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- [1 – (– 2.5)] e – 1 / .01 – .25
- [1 + (– 2.5)] e – 1 / .01 + .25
- does not exist
- 5 u (t – 1)
Correct Option: A
For t > 0 2 u (– t) ⇒ not exist while 50 u (t) → exist, so the circuit becomes like 
| i (∞) = - | = – 2.5 amp. | 20 |
i (0–) = i (0+) = 1 amp.
| τ = | = | = .01 | R | 20 |
we know that
i (t)=[i (0) – i (∞)] e –t / τ + i (∞) .....(i)
on putting the values in equation (i), we get
i (t) = [1 – (– 2.5)] e – t .01 – 2.5
