Question

length of a conducting wire is increased by 100% by stretching it.the change in the resistance of the wire is?

Answer 1

we know,
R= p l/A
Or,R= p l.l/A.l
Or, R = pl.l/V
The initial resistance of wire is show by above equation.
Now,
l = 2l
So,
R'= p. 2l. 2l/V
R'= 4.p.l.l/V
R'=4R
That means when wire is stretching by 100% then resistance of wire becomes 4_ times of initial resistance.