14.Waves and Sound
medium

मूल आवृत्तियों $n_1$ एवं $n_2$ के दो खुली ऑर्गन नलियों को श्रेणी में जोड़ा गया है। इस प्रकार से प्राप्त नई नली की मौलिक आवृत्ति होगी

A

$\frac{{{n_1} + {n_2}}}{2}$

B

$\sqrt {{n_1}^2 + {n_2}^2} $

C

$\;\frac{{{n_1}{n_2}}}{{{n_1} + {n_2}}}$

D

$\;({n_1} + n_2)$

(NEET-2017)

Solution

Fundamental frequency of an open pipe of length $L$ is given by $n =\frac{ v }{2 L }$ $\Longrightarrow L =\frac{ v }{2 n }$

So, we get lengths of two open pipes as $L _{1}=\frac{ v }{2 n _{1}}$ and $L _{2}=\frac{ v }{2 n _{2}}$ Now the pipes are join in series.

Fundamental frequency of new open pipe of length $L _{1}+ L _{2},$

$n =\frac{ v }{2\left( L _{1}+ L _{2}\right)}$

$n =\frac{ v }{2\left(\frac{ v }{2 n _{1}}+\frac{ v }{2 n _{2}}\right)}$

$n=\frac{1}{\frac{1}{n_{1}}+\frac{1}{n_{2}}}$

$\Rightarrow n =\frac{ n _{1} n _{2}}{ n _{1}+ n _{2}}$

Standard 11
Physics

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