Find the resistance of a wire after it is stretched

[collegeconfid]

Homework Statement

A wire is lengthened to 1.25 times its original length by pulling it through a small hole. Find the resistance of the wire after it is stretched.

Homework Equations

resistance=(resistivity)(length)/(area)

The Attempt at a Solution

Umm..the reasoning behind this is that the initial area times length should equal the final area times length. However, I am not sure why this "conservation of volume" applies. Is it because the current is constant so the volume must remain constant?

What does it mean pulling it through a small hole?

 

[mgb_phys]

Volume is conserved because you aren't changing the amount of metal or the density.

So yes the area is reduced by a factor of 1.25, less area means more resistance.