A closed argon pipe and an open argon pipe are tuned to the same fundamental frequency. What is the ratio of their lengths?

• 1:2

• 2:1

• 2:3

• 4:3

There are 26 tuning forks arranged in the decreasing order of their frequencies. Each tuning fork gives 3 beats with the next. The first one is octave of the last. What is the frequency of 18th tuning fork?

• 100 Hz

• 99 Hz

• 96 Hz

• 103 Hz

A person is observing two trains one coming towards him and other leaving with the same
velocity 4 m/s. If their whistling frequencies are 240 Hz each, then the number of beats per second heard  by the person will be : ( if velocity of sound 320 m/s)

• 3

• 6

• 9

• zero

A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is

• 9:4

• 2:3

• 3:2

• 4:9

Two vibrating tuning forks produce progressive waves given by y₁ = 4 sin 500 πt and y₂ = 2 sin 506 Πt. Number of beats produced per minute is

• 360

• 180

• 3

• 60

An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency ?

• Zero

• 0.5 %

• 5 %

• 20 %

The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double of those of room A?

• 2

• 4

• $\frac{1}{2}$

• 1

158.

Which one of the following statements is true?

• Both light and sound waves in air are transverse

• The sound waves in air are longitudinal while the light waves are transverse

• Both light and sound waves in air are longitudinal

• Both light and sound waves can travel in vacuum

A closed organ pipe of length 20 cm is sounded with tuning fork in resonance. What is the frequency of tuning fork? (v = 332 m/s)

• 300 Hz

• 350 Hz

• 375 Hz

• 415 Hz

Two vibrating strings of the same material but lengths L and 2L have radii 2r and r respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length L with frequency ${\mathrm{v}}_1$ and the other with frequency ${\mathrm{v}}_2$ The ratio $\raisebox{1ex}{${\mathrm{v}}_1$}\!\left/ \!\raisebox{-1ex}{${\mathrm{v}}_2$}\right.$ is

• 2

• 4

• 8

• 1