# I have a trivial question about circuit

Discussion in 'General Electronics Chat' started by Manicarus, Apr 10, 2015.

1. ### Manicarus Thread Starter New Member

Apr 10, 2015
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Hi, I am new here and I have a question to ask.

Sorry that I couldn't upload the photo right next my question.
It's in the "Attached Files" corner.

In each circuit, there's a resistor and a battery.
The two circuits are sharing ground.

Is there current flowing through the line between the two circuits?
I am not sure but I remember my professor saying that
logically, there should be no current flowing through it
but in reality, there's a current flow.

Thanks.

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2. ### dl324 Distinguished Member

Mar 30, 2015
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Is this a homework problem?

3. ### Manicarus Thread Starter New Member

Apr 10, 2015
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Nope, this is not a homework but I got curious about it when studying bipolar transistors.

4. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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According to the diagram there will be no current flowing.
Cause there is only one connection and no other path to complete the circuit.
If there is a voltage difference between the batteries there might be negligible current flow.

5. ### dl324 Distinguished Member

Mar 30, 2015
3,376
651
In an ideal situation, there would be no current because everything is at the same potential.

6. ### Manicarus Thread Starter New Member

Apr 10, 2015
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Thank you guys!

7. ### WBahn Moderator

Mar 31, 2012
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What was the professor's reasoning for saying that there is a current flow in reality?

If current is flowing in the line between the two circuits, where is it going? How is it getting back to where it started? If it isn't getting back, then one side is getting an increasingly positive charge and the other side is getting an increasingly negative charge. That means that a potential difference is building up that opposes further current? What mechanism is supporting this? Where is the necessary energy coming from to continue moving charge against this ever increasing potential difference?

8. ### Ramussons Active Member

May 3, 2013
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Mind explaining how?

9. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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I said might due to a Potential difference. Just guessing .

10. ### Ramussons Active Member

May 3, 2013
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That guess is wrong.

R!f@@ and ErnieM like this.
11. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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So tell us what you know. After all, isn't that why you are here.

12. ### KMoffett AAC Fanatic!

Dec 19, 2007
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As WBahn said there is no return path for current to flow into and out of the single common connection. Each battery/resistor is a closed loop. There is no potential difference between the wire going into the common from the right and the one from the left. There may be a potential difference between the left end of R1 and the right end of R2, but again there is no return path for current to flow....as in an open circuit.

Ken