Question

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

• A. Maximum when the battery is connected across 1 cm × $\frac{1}{2}$cm faces.
• B. Maximum when the battery is connected across 10 × 1 cm faces.
• C. Maximum when the battery is connected across 10 cm × $\frac{1}{2}$cm faces
• D. Same irrespective of the three faces.

Answer 1

Answer: (A)

Maximum when the battery is connected across 1 cm × $\frac{1}{2}$cm faces.

Answer 2

: As,$R = \rho\frac{l}{A},$ resistance is maximum when l is large and A is least. For the given dimensions of wire, resistance will be maximum for l = 10 cm and

$A = 1cm \times \frac{1}{2}cm.$