# Trouble understanding how voltage is applied across branches and nodes [closed]

1.We are doing circuit analysis and college and I cannot fundamentally understand how voltage is applied across all of the branches and nodes when using Norton's or Thevinin's Theorem to solve circuits. For eg, if finding the Norton's current across the short circuited node (where the load resistor was) , I just assume that the voltage of the source is the voltage across that node, but turns out it is not? I also assume that the source voltage will be the voltage across all the resistors, but again turns out that is not the case. I understand that the voltage across a resistor will be equal to the source voltage if it is connected in parallel, but if the question has other configurations, I feel like I missed a step somewhere in my understanding. When we are using complicated nodal analysis methods, I am unable to figure out which voltage is unknown or which is known , because I think because I know the source voltage , I can just apply it. And having a bad teacher doesn't help. I was thinking if any of you would be able to point out my flaw in understanding.

1. Also, how do we intuitively know tricks like that of dangling resistors or short-circuited resistors, do they come from practice or are these to be systemically understood?
• Adding a circuit diagram would make this question much easier to understand. Nov 5, 2022 at 17:18
• I myself was struggling to articulate it, but I will try to find one to illustrate it asap! Nov 5, 2022 at 17:21
• You could draw one. Nov 5, 2022 at 17:34
• In any case, I struggled for a long time to get my head around this kind of thing, until I started thinking of the laws of physics (like Kirchhoff's laws etc.) as constraints. The equation $V = I R$ means that whatever the voltage may be, the current is related by that equation. Equivalently, whatever the current may be, the voltage is related by that equation. I find it helpful to think of the equation without any of the variables being "given"... the equation just is. In some circuits, we know the voltage from the beginning while in other circuits we know the current. Nov 5, 2022 at 17:36
• Your question needs clarity. In the meantime do a Google search for Thévenin's theorem. Nov 6, 2022 at 8:45