The resistance of a wire is ‘R’ ohm. If it is melted and stretched to 'n' times its original length, its new resistance will be

The resistance of a wire of length l and area A and resistivity ρ is given asR=ρlA Given, l'=nlAs the volume of the wire remains constant ∴A'l'=AlA'=All'=Alnl   or   A'=An∴R'=ρl'A'=ρnlAn=n2ρlA=n2R