Q. 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
Explanation
[Solution from source] Extension ΔL = FL/(AY) ∝ L/d² for the same material and tension. L/d² = 50/0.25 = 200, 100/1 = 100, 200/4 = 50 and 300/9 ≈ 33 (cm/mm²), so the 50 cm, 0.5 mm wire stretches most. The longest wire is not the answer because its larger area wins. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.