# finding I(current)

I am learning about step response in RC and RL circuits and one of the problems i managed to redraw as the image above; however, when I am solving for i the answer is -5mA. I am just confused on why it is negative as soon in the image, I understand that I just use ohms law here to attain i. In other words how do I add the two voltage sources? I keep getting confused because natural i would have put 120-5 which yields a positive. Can anyone explain why it is 5-120?

• You used 120V node as your reference, so the current is negative. If you use the 5V node as your reference, the sign would have been positive. Notice that the arrow for i points in the correct way to find -5mA, in that regard your found answer is correct. – jippie Apr 14 '15 at 6:59
• sorry I still do not comprehend, may you please explain a bit further? The way I see it is that the current is entering +120 and then hits -5, which is why I have the urge to have 155, not -155. May you please explain it how you go about it? And is the 120 node the reference because the current is traveling to it first? – Learn Apr 14 '15 at 7:09