Q102 / 150 · MHT CET 2020 (16 Oct Shift 2) · Physics

Two wires $A$ and $B$ are stretched by the same load. The radius of wire $A$ is double the radius of wire $\mathrm{B}$. The stress on the wire $\mathrm{B}$ as compared to the stress on the wire A is

  • A
    twice
  • Correct answer
    B
    four times
  • C
    half
  • D
    equal

Solution

(B) stress $=\frac{\text { Force }}{\text { Area }}$ $\therefore$ stress $\propto \frac{1}{\pi r^{2}}$ Thus, $\frac{S_{B}}{S_{A}}=\left[\frac{r_{A}}{r_{B}}\right]^{2}=(2)^{2} \Rightarrow S_{B}=4 S_{A}$

Hence, the correct answer is option: 'B'.

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