# Finding expression for current through resistor

Discussion in 'Homework Help' started by boks, Dec 17, 2008.

1. ### boks Thread Starter Active Member

Oct 10, 2008
218
0

I want to find an expression for $I_5$.

I see that $I_{S1} = I_4 - I_5$, but how can I proceed from here?

Last edited: Dec 17, 2008
2. ### mik3 Senior Member

Feb 4, 2008
4,846
69
Find the Norton equivalent circuit for the terminal across R5 and then calculate I5.

3. ### boks Thread Starter Active Member

Oct 10, 2008
218
0
I think I figured it out:

$I_{S1}=I_4 - I_5$

and $-I_5 (R_1 + R_5) = I_4 R_4$

Solving for I_5 gives

$I_5 = \frac{-I_{S1} R_4}{R_4 + R_5 + R_1}$