1. The problem statement, all variables and given/known data See pic for problem statment and diagram (we are dealing with the diagram on the right) http://i.imgur.com/Uv7Ikma.png I'll rewrite the problem statement here if that helps: Find R_T in the diagram for the cases where ab is open circuited and short circuited. And its solution in the textbook: The first part of is part a) the second part b) http://i.imgur.com/yYLGoFE.png Why is it that after combining the top two resistors and combining the bottom two resistors in the picture that the two resulting series combinations are parallel to each other? 2. Relevant equations None, this is conceptual 3. The attempt at a solution part a) I drew what I think combining the top two and bottom two resistors would look like here in part a for the open circuit case: http://i.imgur.com/Uv7Ikma.png In the pic with the shadow of the hand below, I draw more pictures and I dont' see why the circuit has anything parallel http://i.imgur.com/azqgWwD.png The picture drawn on the right labeled "parallel" was just for me to visually compare the left to see where the "two series combinations are in parallel" in the part a) solutions but I don't see how it leads to the statement in the solutiosn "The two series combinations are in parallel" for part a) which is the first solution in the solution imgur link In part b) the short circuited case, I have also drawn what I believe to be equivalent circuits in the short circuited case but dont understand why the 40/60 combo and 90/10 combo mentioned in the solutions are in series http://i.imgur.com/h4X5Dcn.png What are some smarter ways to draw the circuits to better see why certain combinations are in parallel or series?