A metal rod of length 10 cm and a rectangular cross-section $1 ~cm \times \frac{1}{2} ~cm$ is connected to a battery across opposite faces. The resistance will be :

maximum when the battery is connected across $1 ~cm \times \frac{1}{2} ~cm$ faces.

$ R = \rho \frac{l}{A} $ $\Rightarrow \text{R will be maximum if length is maximum and area is minimum}$

$\Rightarrow \text{ For maximum Resistance length should be 10 cm and area should be }1\times \frac{1}{2}$