# superpostion

#### kana

Joined Sep 19, 2004
4
hello guys
please i need help in this circuit as soon as possiable .... plz !!

:unsure:

i dont know how to solve it

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#### Battousai

Joined Nov 14, 2003
141
Originally posted by kana@Oct 10 2004, 01:09 PM
hello guys
please i need help in this circuit as soon as possiable .... plz !!
:unsure:

i dont know how to solve it
[post=2861]Quoted post[/post]​
First of all, what are you solving for?

There are four nodes: one on the left, one in the middle, one on the right, and ground (bottom).

But essentially you can treat the nodes in the middle and on the right as a single "supernode." With Vright = Vmiddle + Vs2 (eq1)

Now just use Kirchoff's Current Law (KCL) to write equations to determine the desired unknowns.

KCL states that "all current entering a node must sum to 0"

So using Ohm's law, I=V/R

The current entering the middle node from the left node is:

Ileft = (Vleft-Vmiddle)/R1 (eq2)

The current entering the middle node from ground is:

Iground = (0-Vmiddle)/R2 (eq3)

And finally, the current entering from the right-most node is:

Iright = (0-Vright)/R3 (eq4)

Applying KCL: Ileft+Iground+Iright=0 (eq5)

Also we know Vleft=Vs1.

Now you have five equations and five unknowns... so solve.

Hope this helps.