Question

resistance of a wire is 8 ohms it is drawn in such a way that it experiences a longitudinal strain of 400% the new resistance iscan't anyone help me ?

Answer 1

let initial length is l,since longitudnal starin is 200 % then change in length is also 200%let final lenth is ll'−ll×100 = 200l'= 3lResistance is given by:R = ρLAsince volume of the wire will remmains same hencenew arae is A'Al= A'L'Al = A'(3l)A'= A/3new resistance is R'R'R= ρL'A'ρL*A=3lA/3l/A=R'= 9*2=18 ohm