Question

if R is the resistance of the wire of length l and area of cross section A with resistivity row what will the new resistance of the wire if length become half by compressing

Answer 1

R=pl/a------ (1) (p=rho)
R'=pl/2/A
   =pl/2A
   =1/2*pl/A
 R' =1/2 R   (from eq 1)

hope it helps...good luck...