Question

A wire of resistance `R` is elongated `n-fold` to make a new uniform wire. The resistance of new wire.
A. nR
B. `n^(2)R`
C. `2nR`
D. `2n^(2)R`

Answer 1

Correct Answer - B
The resistance of a wire is directly proportional to the length of the wire. Thus `R prop l`, so the length increases n-fold also since the volume of the wire remains constant, so the area of the wire decreases n-fold. Hence, the resistance increases to `n^(2)R` as the area is inversely proportional to resistance.