Question

A copper wire of resistivity P is stretched to reduce its diameter to half its previous value. what is the new resistivity?

Answer 1

the new restivity is 2P

Answer 2

THERE WILL BE THERE NO CHANGE IN THE RESISTIVITY  BECAUSE THE WIRE IS STRETCHED WHICH MEANS THAT WE HAVE NOT JOINT ANOTHER WIRE . THE RESISTIVITY DEPENDS ON THE NATURE OF THE MATERIAL AND TEMPERATURE . SO BY STRETCHING THE WIRE WE HAVE TO CHANGED THE NATURE OF THE MATERIAL SO THE RESISTIVITY IS THE SAME.