Need to find two currents in this circuit

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opticaltempest
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I am trying to find the currents I_D1 and I_D2 labeled in the picture by the arrows. I am stumped on how to obtain the correct values for the currents. I am having trouble using either KCL or KVL. This circuit seems simple but has me stumped.

http://img127.imageshack.us/img127/8600/circuitvz9.jpg

If I write KCL at the node to the right of the I_D1 arrow I get

[tex]-I_{D1}+I_{D2}-I_{6V}=0 \implies[/tex]

[tex]I_{D1}=I_{D2}-I_{6V}.[/tex]

[tex]I_{6V}=\frac{6V}{43k\Omega}=140\mu A[/tex]

[tex]I_{D2}=\frac{9V}{22k\Omega}=409\mu A[/tex]

Is there an easier or different way to do this problem, perhaps using KVL instead of writing a KCL equation at the node I used?

Thanks
 
Last edited by a moderator:
Yes you can also do it via mesh analysis. You would have 2 equations here.
 
opticaltempest said:
I am trying to find the currents I_D1 and I_D2 labeled in the picture by the arrows. I am stumped on how to obtain the correct values for the currents. I am having trouble using either KCL or KVL. This circuit seems simple but has me stumped.

http://img127.imageshack.us/img127/8600/circuitvz9.jpg

If I write KCL at the node to the right of the I_D1 arrow I get

[tex]-I_{D1}+I_{D2}-I_{6V}=0 \implies[/tex]

[tex]I_{D1}=I_{D2}-I_{6V}.[/tex]

[tex]I_{6V}=\frac{6V}{43k\Omega}=140\mu A[/tex]

[tex]I_{D2}=\frac{9V}{22k\Omega}=409\mu A[/tex]

Is there an easier or different way to do this problem, perhaps using KVL instead of writing a KCL equation at the node I used?

Thanks

The simplest way to solve the circuit is the one you used.
 
Last edited by a moderator:
Quick solution:

Hey this is a simple mesh anaylisis problem.. I've included a solution. I hope it helps. Cheers
 
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  • Two-loop mesh analysis circuit schematic with 6 V source V3 and 43kΩ resistor R3 in the upper loop, 9 V source V4 and 22kΩ resistor R4 in the lower loop, mesh currents i-1 and i-2, and handwritten working for I_D and I_D2 in micro amps.
    optical-tempestsprob.JPG
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