Question

A pipe of length $${\ell _1},$$ closed at one end is kept in a chamber of gas of density $${\rho _1}.$$ A second pipe open at both ends is placed in a second chamber of gas of density $${\rho _2}.$$ The compressibility of both the gases is equal. Calculate the length of the second pipe if frequency of first overtone in both the cases is equal

A. $$\frac{4}{3}{\ell _1}\sqrt {\frac{{{\rho _2}}}{{{\rho _1}}}} $$
B. $$\frac{4}{3}{\ell _1}\sqrt {\frac{{{\rho _1}}}{{{\rho _2}}}} $$  
C. $${\ell _1}\sqrt {\frac{{{\rho _2}}}{{{\rho _1}}}} $$
D. $${\ell _1}\sqrt {\frac{{{\rho _1}}}{{{\rho _2}}}} $$
Answer :   $$\frac{4}{3}{\ell _1}\sqrt {\frac{{{\rho _1}}}{{{\rho _2}}}} $$
Solution :
Frequency of first overtone in closed pipe,
$$v = \frac{{3v}}{{4{\ell _1}}}\sqrt {\frac{P}{{{\rho _1}}}} \,......\left( {\text{i}} \right)$$
Frequency of first overtone in open pipe,
$$v' = \frac{1}{{{\ell _2}}}\sqrt {\frac{P}{{{\rho _2}}}} \,......\left( {{\text{ii}}} \right)$$
From equation (i) and (ii)
$$ \Rightarrow {\ell _2} = \frac{4}{3}{\ell _1}\sqrt {\frac{{{\rho _1}}}{{{\rho _2}}}} $$

Releted MCQ Question on
Oscillation and Mechanical Waves >> Waves

Releted Question 1

A cylindrical tube open at both ends, has a fundamental frequency $$'f'$$ in air. The tube is dipped vertically in air. The tube is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column in now

A. $$\frac{f}{2}$$
B. $$\frac{3\,f}{4}$$
C. $$f$$
D. $$2\,f$$
Releted Question 2

A wave represented by the equation $$y = a\cos \left( {k\,x - \omega t} \right)$$    is superposed with another wave to form a stationary wave such that point $$x = 0$$  is a node. The equation for the other wave is

A. $$a\sin \left( {k\,x + \omega t} \right)$$
B. $$ - a\cos \left( {k\,x - \omega t} \right)$$
C. $$ - a\cos \left( {k\,x + \omega t} \right)$$
D. $$ - a\sin \left( {k\,x - \omega t} \right)$$
Releted Question 3

An object of specific gravity $$\rho $$ is hung from a thin steel wire. The fundamental frequency for transverse standing waves in the wire is $$300\,Hz.$$  The object is immersed in water so that one half of its volume is submerged. The new fundamental frequency in $$Hz$$  is

A. $$300{\left( {\frac{{2\,\rho - 1}}{{2\,\rho }}} \right)^{\frac{1}{2}}}$$
B. $$300{\left( {\frac{{2\,\rho }}{{2\,\rho - 1}}} \right)^{\frac{1}{2}}}$$
C. $$300\left( {\frac{{2\,\rho }}{{2\,\rho - 1}}} \right)$$
D. $$300\left( {\frac{{2\,\rho - 1}}{{2\,\rho }}} \right)$$
Releted Question 4

A wave disturbance in a medium is described by $$y\left( {x,t} \right) = 0.02\cos \left( {50\,\pi t + \frac{\pi }{2}} \right)\cos \left( {10\,\pi x} \right)$$        where $$x$$ and $$y$$ are in metre and $$t$$ is in second

A. A node occurs at $$x = 0.15\,m$$
B. An antinode occurs at $$x = 0.3\,m$$
C. The speed wave is $$5\,m{s^{ - 1}}$$
D. The wave length is $$0.3\,m$$

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