# Time constant in LR circuits.

Discussion in 'Homework Help' started by sunny1982, Apr 1, 2013.

1. ### sunny1982 Thread Starter Member

Dec 27, 2012
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0
<P>Hi folks can someone please check if this is correct and give me a pointer to the question that i haven't answered please. The question is the time it takes for the current to settle down. Many thanks.</P>

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2. ### Jony130 AAC Fanatic!

Feb 17, 2009
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We usually assume that steady-state is reached after 5*tau.
So for L = 10H and R = 100Ω we have time constant
t = 10H/100Ω = 0.1s = 100ms and we reach steady-state after 5*0.1 = 0.5s.

3. ### WBahn Moderator

Mar 31, 2012
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7,382
Gee, Jony130, if we are going to turn this into the Homework Done For You forum, why not offer to submit the answer directly to the instructor?

Please don't just work a student's problem for them. If that was all they needed to learn the material, then they would of gotten it already from the examples in the text or worked in class. They need to struggle with the concepts a bit on their own in order to find their way and we need to guide them, not just blindfold them and drag them to the destination leaving them just as lost as when they started.

4. ### sunny1982 Thread Starter Member

Dec 27, 2012
41
0
Thankyou very much, I was wondering if you managed to check if the rest of the questions were correct.