# Calculate the current

1. Sep 19, 2008

### john88

1. The problem statement, all variables and given/known data

2. Relevant equations

KCL

3. The attempt at a solution

I have some question for this circuit.

http://img510.imageshack.us/my.php?image=questpt3.jpg

I want to calculate the current I, my first thought was that it cant go any current because the potential difference is zero. But then I thought that the current source can produce a current even if there is zero potential, so there is a current I anyway. I am correct?

I would appreciate some help.

2. Sep 19, 2008

### Defennder

There will be a current through the wire. The potential difference across any ideal wire is 0, but still there will be current flow if the other circuit element are present. You can make use of superposition principle to do this problem.

3. Sep 19, 2008

### john88

ok so if I use the superposition method I get this:

First I have this situation

http://img387.imageshack.us/my.php?image=firstum9.jpg

First I replace the current source whit an open circuit and I end up whit this:

http://img66.imageshack.us/my.php?image=second2ud4.jpg

So I = -(2.71/R9)

Next I replace the voltage source whit a short-circuit

http://img399.imageshack.us/my.php?image=second1br1.jpg

(im not sure if that step is right, I replaced the voltage source whit a short-circuit. So the resitance R10 got short circuted and I took it away correct?)

Then I = I1 (current source) not sure of that either....

which means that the total current I is equal to I1 -(2.71/R9)

4. Sep 19, 2008

### Defennder

You could have just reverse the direction of the battery instead of writing a negative voltage source, you know.

What happened to the 2k resistor?

Yes, and so is the R9 resistor, so you have I = I1 here as well.

5. Sep 24, 2008

### john88

Well ye I took away the 2k resistor, and thats not correct but I still end up whit the same answer when I use the current divider, but its not negative. I = 2.72/6500

So now I_tot = I + I1

This must be the right answer

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