# Complex Parallel Resistor Problem

#### Tesla23

Joined May 10, 2009
536
Lots of 3D confusion.

R2 and R5 are shorted out, R1, R3, R4 and R6 are connected across the inputs,

$R_{T} = \frac{1}{1/R_1+1/R_3+1/R_4+1/R_6} = 10$

• seanstevens

#### SamR

Joined Mar 19, 2019
4,818
I see that R2 is shorted but not R5. Ahhh... Now I see it, K, thanks!

#### WBahn

Joined Mar 31, 2012
29,165
• SamR, narkeleptk and sghioto

#### MrAl

Joined Jun 17, 2014
10,606
Been working with this all day and can't quite suss it out. Reduced it down as much as I could and was given the answer is Rt=10Ω. But... R2 is giving me headaches. Can't quite see what I'm missing...
View attachment 295331

Hi there,

As others have already pointed out, when you consider the 6 edges that are not resistors but just shorts, the circuit looks like it becomes greatly simplified.
If that wasn't the case though and you had a complete cube where all edges were actually resistors of different values, a simpler way to solve it is to start by solving for the voltages at the two nodes that R1 is connected to. You can then go on to figure out the value. If you did not have an input to the circuit and just needed to calculate the equivalent resistance, you could use an assumed current like 1 amp or possibly an assumed voltage like 1v, then go from there. That's a very general method although it does take some work.

• SamR