Physics - Current Electricity Question with Solution | TestHub

Let the square corners be A, B, C, D in clockwise order. The additional wire connects A and C. We need to find the equivalent resistance between A and B. The circuit forms a Wheatstone bridge like structure. Resistors are AB, BC, CD, DA, and AC, all of resistance R. If current enters at A and leaves at B, paths are A-D-C-B, A-C-B, and A-B. This can be solved using Kirchhoff's laws or by identifying series/parallel combinations after redrawing. The equivalent resistance between A and B is $\frac{7R}{12}$.