Question

The diagram shows different copper conductors of diameters (d) and (2d) and lengths, which are multiples of (l). The increasing order of their resistances will be:

Options

• A < B < C < D

• A < C < D < B

• A < D < C < B

• D < A < C < B

Answer 1

D < A < C < B

Explanation:

For the same material, \(R = \rho l/A\), and since \(A \propto d^2\), \(R \propto l/d^2\). From the figure: A has 1 unit, B has 4 units, C has 2 units, and D has \(2/4 = 1/2\) units of resistance.

Therefore, the increasing order is D < A < C < B.