1. The problem statement, all variables and given/known data Find the power absorbed by element X, if it is 4000 Ohms. (See attached picture for circuit) 2. Relevant equations KCL: Sum of Currents into Node Must = 0 3. The attempt at a solution I've already worked through a bunch of these type of problems, but I always mess up on which currents are positive and which ones are negative...which ultimately leads to the wrong answer. I know on this specific problem, the whole idea is to apply KCL in order to obtain a Voltage. That voltage will then be multiplied by 40 Ohms to give you the power absorbed by the resistive element. I think my lack of understanding of KCL is keeping from getting these ideas. I guess as I run this problem through my head I use a reference location at the node above the 1000 Ohm resistor. And from my thinking I would come up with the following equation... 0=(.08)A - (v/1000[ohms])A - (.03)A - (v/4000[ohms])A Then I would solve for V, but it ends up giving me the wrong answer. I'm assuming one of my values should be negative?
Nevermind! Figured it out. The equation above is correct, it's when I was adding and subtracting to the opposing sides, I kept seeing .08A as -.08A. It computes out to 40V on the Resistor. Then I use P=V2/R to obtain .4 Watts.