A wire of resistance 4 Ω is stretched to twice its original length. The resistance of stretched wire would be:
Options

Question

A wire of resistance 4 Ω is stretched to twice its original length. The resistance of stretched wire would be:

G1 Physics · Accepted Answer

Step 1: On stretching, volume remains fixed: A₁L₁ = A₂L₂. Step 2: L₂ = 2L₁ ⇒ A₂ = A₁/2. Step 3: R₂ = ρ(2L₁)/(A₁/2) = 4R₁ = 16 Ω.