Question

A wire of Length L and resistance R is stretched so that its length is doubled and the area of cross section is halved ,How will its a. resistance change ?b.resistivity change

Answer 1

•Resistivity will be same since it is independent of Length

•Now , Let p denotes resistivity of wire ,

Using , R = pL/A --(1)

Let R' be the resistance after stretching
so ,
R' = p2L/A/2

R' = 4pL/A---(2)

> Dividing both

R/R' = 1/4

R' = 4R

• So wire resistance will become four times of its initial value