Q 12-03-099JEE MainJEE Main 2024 (9 Apr, Shift 2)Medium
The effective resistance between $A$ and $B$, if the resistance of each resistor is $R$, will be:
Answer: (A) $\dfrac{8R}{3}$
The diamond is symmetric about its vertical diagonal, so the top, centre and bottom nodes are all at the same potential (midway between the left and right nodes). No current flows in the two vertical resistors.
Between the left and right nodes there are then three identical paths of $2R$ each (top, middle, bottom), in parallel: $\dfrac{2R}{3}$.
$$R_{AB} = R + \frac{2R}{3} + R = \frac{8R}{3}$$
Solution by Sreeraj P, M.Sc Physics