Question

Due to the stretching the length increase by 20%, then the corresponding change in the resistance is

Answer 1

If, length= l and resistance (R) =pl/A=p(l^2)/V
where p=resistivity
l=length
A= area
V=volume

Then , increase in length = l*20/100

l'= l+(l/5)

l'=6l/5

Final resistance
= p( l'^2)/V

R'=p *36(l^2)/25V

R'=(36/25)R

Increase in resistance (%) ={( R'-R) /R}*100

=11R*100/25R %

=44%