# Why is a resistor between a node and a current source not considered when doing node-voltage method? I'm trying to get V2. When looking at the solution, I see that for the node V3, this is what they have:

$$\frac{V_3}{100}+\frac{V_3-V_4}{200}=0.15A$$

I'm wondering why they're not considering the 200ohm resistor to the left of V3? Initially, I thought the node equation would look like this:

$$\frac{V_3}{100}+\frac{V_3-V_4}{200}+\frac{V_3-V_2}{200}=0.15A$$

Thanks.

• Because you know what the current through it is already, that's where the 0.15 A figure comes from. This isn't an answer because it doesn't also address the way you're ignoring the current source in your added term, and I don't have the energy to explain all that right now. Oct 31, 2021 at 18:15
• 200 + infinity equals ??? Oct 31, 2021 at 18:16
• Swapnil, one more thing to add to what others have said. The current source determines the current. The resistor has no impact whatsoever on that branch current. The only impact the resistor has in this circuit is to adjust the voltage across the current source, itself (the resistor's voltage drop making up whatever remains.) The voltage difference at the two ends of the branch is identically the same, with or without the resistor. $V_2$ and $V_3$ won't change if you change the resistor value.
– jonk
Oct 31, 2021 at 18:23
• The answer is in the 2nd comment. CC has infinite impedance. Oct 31, 2021 at 18:42