# RC time constant...

Discussion in 'General Electronics Chat' started by i3ill, Dec 7, 2008.

1. ### i3ill Thread Starter New Member

Dec 7, 2008
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Doing some homework for my basic DC electronics class and do not know how to answer this question!
The RC time constant of a circuit consisting of a 10k resistor in series with a 50 uF capacitor is _______. When a power supply is connected to this RC circuit, it is generally considered that the capacitor will be fully charged in ________ time constants, which would be ________ seconds.

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2. ### hgmjr Moderator

Jan 28, 2005
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What answers have you been able to calculate on your own?

hgmjr

3. ### Wendy Moderator

Mar 24, 2008
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Concerning the 1st problem, this is one of those rare situations the description is also the equation.

May 16, 2005
5,072
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5. ### Wendy Moderator

Mar 24, 2008
20,735
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I just reviewed the chapter, it doesn't give the answer for the 2nd question. I remember the answer from my school days. Till the OP gets the first problem I'm not too worried about it though.

6. ### TanTJ Member

Mar 6, 2008
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I'm pretty sure I know the answer as well, but don't want to give it away. Is the answer to the second part of the question the derivative of the function f(x)=5x+7? If you get my meaning

7. ### jpanhalt AAC Fanatic!

Jan 18, 2008
5,561
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Isn't the second part like similar questions related to any rate equation? That is, what do you consider fully charged, reacted, or whatever: 86%, 95%, 99%, etc? The answer will be what the instructor told you. The exponent is usually 3, 4, or 5 for practical purposes. I tend to prefer 4 or even 3, if the time constant is long; although, some people stick rididly to 5 (99%).

John

8. ### Wendy Moderator

Mar 24, 2008
20,735
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That's what I was taught...