# RC response problem

Thread Starter

#### PG1995

Joined Apr 15, 2011
816
Hi

I'm trying to solve Practice Problem 7.10. But I'm stuck. I'm not even sure if my procedure is correct. Please help me with it. Many thanks.

Regards
PG

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#### Jony130

Joined Feb 17, 2009
5,155
Why you use mesh analysis instead of Ohms law for such a simple circuit?

The right voltage source is equal to 50V not 5V.

And the current is simply equal to:
I' = 10V/8Ω = 1.25A
And
I'' = 50V/8Ω = 6.25A

Itotal = I' + I'' = 1.25A + 6.25A = 7.5A

Or as you should see from the diagram, that the two voltage source are connect in series.
So we can write by inspection

Itot = ( 10V + 50V) /8Ω= 7.5A

So V(∞) = -5V

And now you can start to find the time constants.

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Thread Starter

#### PG1995

Joined Apr 15, 2011
816
Thank you, Jony.

I realize it now. The hard copy of the book I have is 3rd edition while the e-book version is 4th ed. I think there was a mistake in 3rd edition which I was using. So, it's 50V, not 5V.

By the way, how do we solve such problems on circuit simulators such as Multisim or Circuit Wizard?

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