Question

which of the following copper rods has a higher resistance across its ends? a. b.

Explanation:

Step1: Recall resistance formula

The resistance formula is $R =
ho\frac{l}{A}$, where $
ho$ is the resistivity (constant for copper), $l$ is the length and $A$ is the cross - sectional area. Assuming the cross - sectional area is the same for both rods, resistance is directly proportional to length.

Step2: Compare rod lengths

From the image, rod B is longer than rod A. Since $R\propto l$ (with $
ho$ and $A$ constant), rod B has higher resistance.

Answer:

B.