KVL is just not working out for me. Conceptually it makes total sense, but there's some key detail I'm missing because algebraically I'm finding that "arbitrarily" choosing current direction dramatically changes the answer - not just a negative / positive reversal.
Here's a simple example circuit diagram I found where KVL does not appear to work when I execute it by plugging in the voltages (using Ohm's law with the 2A answer they got and the given resistances) despite that very document showing how it works no matter which arbitrary direction you chose for current.
http://web.engr.oregonstate.edu/~traylor/ece112/lectures/kvl_analysis.pdf
Using that circuit diagram, if I choose current to go clockwise, I get this:
R1 = 30 Ohms X 2 A = 60V
R2 = 15 Ohms x 2 A = 30V
So,
-120V + 60V + 30V + 30V = 0
No problem, that looks great. So what if I chose current to go counter-clockwise instead? I get this:
-120V - 60V + 30V - 30V = 0
That's not right. That's -180, not 0. What in the world am I doing wrong here? I stare and stare at this, and I'm just not seeing it. That equation comes straight out of their own example, merely plugging in the actual voltage value, E, in place of the IR term.
Here's a simple example circuit diagram I found where KVL does not appear to work when I execute it by plugging in the voltages (using Ohm's law with the 2A answer they got and the given resistances) despite that very document showing how it works no matter which arbitrary direction you chose for current.
http://web.engr.oregonstate.edu/~traylor/ece112/lectures/kvl_analysis.pdf
Using that circuit diagram, if I choose current to go clockwise, I get this:
R1 = 30 Ohms X 2 A = 60V
R2 = 15 Ohms x 2 A = 30V
So,
-120V + 60V + 30V + 30V = 0
No problem, that looks great. So what if I chose current to go counter-clockwise instead? I get this:
-120V - 60V + 30V - 30V = 0
That's not right. That's -180, not 0. What in the world am I doing wrong here? I stare and stare at this, and I'm just not seeing it. That equation comes straight out of their own example, merely plugging in the actual voltage value, E, in place of the IR term.