Question

Two aluminium wires are of same length, but one is thicker than the other.

1. Which wire will have more resistance?
2. Which wire will have more specific resistance?

Answer 1

(i) The thinner aluminium wire will have more resistance. Since

R = `ρl/A`

the resistance R is directly proportional to length l and inversely proportional to cross-sectional area A. Both wires have the same length, but the thicker wire has a larger area and hence lower resistance.

(ii) Both wires have the same specific resistance (resistivity), assuming they are at the same temperature. Specific resistance depends on the material and its temperature, not on the wire’s length or thickness.