# Natural Response of an RL circuit

Discussion in 'Homework Help' started by jstrike21, Oct 14, 2009.

1. ### jstrike21 Thread Starter Member

Sep 24, 2009
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On the first problem in the attached pdf, wouldn't Vo(0-) and Vo(0+) be zero due to the inductor acting as a short?

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2. ### ELECTRONERD Senior Member

May 26, 2009
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In terms of resistance, yes, I would say that you're correct. However, inductors do have a negligible amount of resistance that you can ignore, but that certainly doesn't change the inductance. It's still there.

3. ### Thav Member

Oct 13, 2009
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You can only say an inductor acts as a short to DC current. At t=0 there is a transient event in which case the inductor is most decidedly not a short.

The current in an inductor can not change instantaneously. So at t=0+ the current inductor must be the same as it was at t=0-. Where does that current have to flow to complete the circuit? What can you then tell about the voltage across the inductor?

4. ### ELECTRONERD Senior Member

May 26, 2009
1,146
16
That makes perfect sense.