Question

The following four wires are made of the same material. Which of these will have the largest extension when the same tension is applied –

• A. length = 50 cm, diameter = 0.5 mm
• B. length = 100 cm, diameter = 1 mm
• C. length = 200 cm, diameter = 2 mm
• D. length = 300 cm, diameter = 3 mm

Answer 1

Answer: (A)

length = 50 cm, diameter = 0.5 mm

Answer 2

Y = $\frac{mg/A}{\mathcal{l/}L}$= $\frac{mgL}{A\mathcal{l}}$

$\mathcal{l}$ = $\frac{mgL}{YA}$

So $\mathcal{l}$ µ $\frac{L}{d^{2}}$ hence (1)