# Finding the currents in this circuit (2 voltage sources and 3 resistors)

Homework Statement:
Which current ratings do I1, I2 and I3 have if the resistances hold R1 = 0.1 ohm, R2 = 0.02 Ohm and R3 = 0.2 Ohm?
Relevant Equations:
U = IR
1/R = 1/R_1 + 1/R_2 + ....
I1 = I2 + I3
In my attempt, I tried
1) I1 = I2 + I3
Then set up these two equations based on Kirchhoff's second rule:
2) U1 = R1 (I2) + R3 (I3) and
3) U1 + U2 = R1 (I1) + R2 (I3).
From what we have
10 = 0.1* I_2 + 0.2 * I_3
22 = 0.1* I_2 + 0.02*I_3

I_3 = 50 - 0.5 I_2

That means
I_2 = 233.3 A
I_3 = -66.7A
I1 = 166.6A
My answer is completely off.

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## Answers and Replies

phinds
Science Advisor
Gold Member
In my attempt, I tried
1) I1 = I2 + I3
That does not comport with your drawing.

That does not comport with your drawing.
If I fix that part, will the rest be right then?

phinds
Science Advisor
Gold Member
If I fix that part, will the rest be right then?
No. Start there and rework the problem.