Question

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

• A. maximum when the battery is connected across $1 \,cm \times \frac {1}{2}$ cm faces
• B. maximum when the battery is connected across $10 \,cm\, \times \frac {1}{2} cm $ faces
• C. maximum when the battery is connected across $10 \,cm \times$ 1 cm faces
• D. same irrespective of the three faces

Answer 1

Answer: (A)

Resistance is inversely proportional to area.
Hence resistance will be maximum when the battery is connected across $1 \,cm \times$ $(1 / 2) cm$ faces.