Q104 / 125 · BITSAT 2014 · Physics
When a string is divided into three segments of length $l_{1}, l_{2},$ and $l_{3}$, the fundamental frequencies of these three segments are $v_{1}, v_{2}$ and $v_{3}$ respectively. The original fundamental frequency
(v) of the string is
- A$\quad \sqrt{v}=\sqrt{v_{1}}+\sqrt{v_{2}}+\sqrt{v_{3}}$
- B$v=v_{1}+v_{2}+v_{3}$
- Correct answerC$\frac{1}{v}=\frac{1}{v_{1}}+\frac{1}{v_{2}}+\frac{1}{v_{3}}$.
- D$\frac{1}{\sqrt{v}}=\frac{1}{\sqrt{v_{1}}}+\frac{1}{\sqrt{v_{2}}}+\frac{1}{\sqrt{v_{3}}}$
Solution
Fundamental frequency is given by
$$
v=\frac{1}{2 l} \sqrt{\frac{T}{\mu}} \Rightarrow v \propto \frac{1}{l} \Rightarrow P \propto \frac{1}{v}
$$
Since, $P$ divided into $l_{1}, l_{2}$ and $l_{3}$ segments Here $l=l_{1}+l_{2}+l_{3}$
So $\quad \frac{1}{v}=\frac{1}{v_{1}}+\frac{1}{v_{2}}+\frac{1}{v_{3}}$
Hence, the correct answer is option: 'C'.