# Quick question

Discussion in 'Homework Help' started by gicode0823, Apr 10, 2012.

1. ### gicode0823 Thread Starter Member

Feb 8, 2012
31
0
When trying to get Thevenin Equivalent of a circuit, does it matter if circuit is simplified?

2. ### jimkeith Well-Known Member

Oct 26, 2011
539
100
not if done correctly--that is what Thevenin's is all about--simplification

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3. ### gicode0823 Thread Starter Member

Feb 8, 2012
31
0
One more quick question...

If I found the Thevenin Equivalent

Vth = 38 V and Req = -2300 ohm

If I connect voltage independent source and try to find the power deliver from that source, is there anyway I can find which way current is flowing?

4. ### WBahn Moderator

Mar 31, 2012
24,454
7,653
There is no such thing as negative resistance (in a problem such as this). You have done something wrong.

Are you talking about a problem on a piece of paper, or connecting a physical source and determining which way current is flowing between it an a load?

If a physical source into a passive load (and by "passive" here, I mean what that does not have any other power sources from which to draw such that it could be supplying net power to your supply), the current is flowing out of the terminal with the higher voltage, otherwise the load would be supplying power to the source. If it's an active load that has the ability to source power as well, then you can connect the two through a low valued resistor and measure the voltage drop across it. That will tell you both the magnitude of the current as well as the direction.

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5. ### jimkeith Well-Known Member

Oct 26, 2011
539
100
..unless it is imaginary +j or -j reactance in rectangular form

6. ### WBahn Moderator

Mar 31, 2012
24,454
7,653
Then it would be an imaginary reactance and not negative resistance. -2300 ohms is a negative resistance . If the OP meant -j2300 ohms, then saying -2300 ohms is still just as wrong (though it may have just been a typo).