A uniform wire of resistance

PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity

Problem

R_0

, length

l_0

and cross-sectional area

A_0

is stretched slowly and uniformly so that its length becomes

n

times the original length (

n>1

). The stretching is performed without any change in temperature. (i) Derive an expression for the new resistance

R_n

of the wire in terms of

R_0

and

n

, assuming that the volume of the wire remains constant. (ii) Show that

R_n = n^{2} R_0

. (iii) State whether the resistivity of the wire changes as a result of stretching and justify your answer.