Circuit analysis is this correct?

[Questions999]

Homework Statement

We have the the circuit in the figure.

Homework Equations

I have to find I2.
KVL,KCL.

The Attempt at a Solution

I apply KVL in the "left " part of the circuit and I have -42 V+ 2I1 +8I2=0 .(I 1 is the current through 2 Ohm).I apply KCL in the nod between R1 R3 and R2 and I have (Current through R3)=I1-I2. I apply KVL in the right part of the circuit and I have -8I2+4(I1-I2) +2I2=0. I form a system with -42 V+ 2I1 +8I2=0 and -8I2+4(I1-I2) +2I2=0 and here I find that I1=(10/4)*I2.I replace this in 2I1+8I2=42 and I have I2=3.2 A.Is this correct?

 

[gneill]

No, J = 2I₂ is a current source. So your KVL expression for the second loop is not correct; you cannot say offhand what the potential drop across that current source will be.

Note that this current source tells you something about the current flowing through R3...

 

[Questions999]

Oh,that current is 2I.So now I have I1-I2=2I2. Then I1=3I2.I replace this in 2I1+8I2=42. Now I have 14I2=42.Now I2=3 A.Thanks :)