Hey everyone I'm really struggling with assigning polarities and current directions to circuit elements to a circuit. There's an example worked in my book (in fact many) where they'll go from having a circuit and then in the next step polarities and current directions are added to each element without explanation. I wish I could show an image of it but I'll describe the best I can:(adsbygoogle = window.adsbygoogle || []).push({});

Given circuit: There's a circuit with two loops (left and right). The left loop on the furthest left has an independent voltage source of 120V with negative on the bottom and positive on top on the upper part of the left loop is 10 ohm resistor, the right branch of the left loop there's a 50 ohm resistor, and there's an current arrow in the clockwise direction

Right loop: The left branch which is the right branch of the left loop has that previously mentioned 50 ohm resistor obviously, and the right branch of the right loop has an independent current source of 6A in the counterclockwise direction.

I hope you can picture that well. Now in solving this problem the book assigns polarities and current to each element but fails to explain how you know to apply a voltage drop/rise or direction of current so:

The 10 ohm resistor has plus on the left and neg on the right, the 50 ohm resistor has an unknown current in the clockwise direction and the right circuit loop has a plus on top of the loop and negative on the bottom of the loop.

Now I know how to solve this problem. My only question is how on earth did they know what polarities and current directions to assign. If you could break this down simply and not get too conceptual with your explanation I'd greatly appreciate it. The concept I can learn only after I understand a practical, possibly step by step, method to assigning these qualities.

Thanks a ton! Andrew

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# Assigning Polarities and Current Directions

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