Question

When the length of the wire is stretched to its double then what will be the effect on its resistance

Answer 1

Answer:

Resistivity of wire=K

Original length=l

New length(l')=2l

Original area of cross section=A

New area of cross section=A'

Since volume of the wire remains same,

l×A=2l×A'

A'=A/2

Original resistance(R)=Kl/A

New resistance(R')=Kl'/A'=(K×2l)/(A/2)

R'=4Kl/A

R'=4R

So resistance of the wire becomes 4 times