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

Step-by-step solution

Volume of wire will remain constant So, A 1 l 1 = A 2 l 2 ⇒ A 2 = A 1 n The resistance of a wire with a length l , an area of A , and resistivity ρ is stated as R = ρ l A . Now, the new length is n l . ∴   New resistance R ' = ρ n l A / n ⇒ R ' = ρ n 2 l A ⇒   R ' = n 2 R