Question

A metallic wire of length L and radius R is stretched to a length 2L. The Percentage change in the resistance of the wire is
(1) 100%
(2) 200%
(3) 300%
(4) 400%

P.S. I found the answer to be 100% but answer key says its 300%, is the answer key wrong?

Answer 1

Answer:

R=L/A

a/q

if wire is strached to 2L then,

R'=2L/A

R'=2R

therefore ans will be 200%