Q 11 :

A guitar string of length 90 cm vibrates with a fundamental frequency of 120 Hz. The length of the string producing a fundamental frequency of 180 Hz will be ______ cm.     [2023]

Q 12 :

A wire of density $8\times {10}^3{\text{ kg/m}}^3$ is stretched between two clamps 0.5 m apart. The extension developed in the wire is $3.2\times {10}^{-4}\text{ m}$. If $Y=8\times {10}^{10}{\text{ N/m}}^2$, the fundamental frequency of vibration in the wire will be ________ Hz.        [2023]

Q 13 :

For a certain organ pipe, the first three resonance frequencies are in the ratio of 1 : 3 : 5 respectively. If the frequency of fifth harmonic is 405 Hz and the speed of sound in air is 324 ${\mathrm{ms}}^{-1}$, the length of the organ pipe is ______ m.              [2023]

Q 14 :

In an experiment with sonometer, when a mass of 180 g is attached to the string, it vibrates with fundamental frequency of 30 Hz. When a mass m is attached, the string vibrates with fundamental frequency of 50 Hz. The value of m is ______ g.            [2023]

Q 15 :

The fifth harmonic of a closed organ pipe is found to be in unison with the first harmonic of an open pipe. The ratio of lengths of closed pipe to that of the open pipe is $\frac{5}{x}$. The value of $x$ is _______ .            [2026]

• 1

   

• 3

   

• 4

   

• 2

   

Q 16 :

In an open organ pipe $v_3$ and $v_6$ are 3rd and 6th harmonic frequencies, respectively. If $v_6-v_3=2200 \text{Hz},$ the length of the pipe is _______ mm. 

(Take velocity of sound in air is 300 m/s)      [2026]

• 200

   

• 250

   

• 275

   

• 225