Q. $A$ and $B$ are two wires. The radius of $A$ is twice that of $B$. They are stretched by the same load. Then the stress on $B$ is
A) Equal to that on $A$
B) Four times that on $A$
C) Two times that on $A$
D) Half that on $A$
Explanation
(b) $Stress = \frac{force}{Area}\therefore Stress \propto \frac{1}{\pi r^{2}}$
$\frac{S_{B}}{S_{A}} = \left( \frac{r_{A}}{r_{B}} \right)^{2} = (2)^{2} \Rightarrow S_{B} = 4S_{A}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.