Q. Copper of fixed volume 'V' is drawn into wire of length 'l'. When the wire is subjected to a constant force 'F' the extension produced in the wire is 'Δl'. Which of the following graphs is a straight line?
A) Δl versus 1/l
B) Δl versus $l^2$
C) Δl versus $1/l^2$
D) Δl versus l
Explanation
[Solution] $\Delta l = \frac{Fl}{AY}$ with $A = \frac{V}{l}$ gives $\Delta l = \frac{F l^2}{VY}$, so Δl ∝ $l^2$. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.