Q. A wire is loaded by 6 kg at its one end, the increase in length is $12\ mm$. If the radius of the wire is doubled and all other magnitudes are unchanged, then increase in length will be
A) $6\ mm$
B) $3\ mm$
C) $24\ mm$
D) $48\ mm$
Explanation
(b) $l \propto \frac{1}{r^{2}}$, if radius of the wire is doubled then increment in length will become $\frac{1}{4}$ times $i.e.\frac{12}{4} = 3mm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.