Interference of Sound Waves

IMPORTANT

Interference of Sound Waves: Overview

This topic covers concepts, such as, Condition for Constructive Interference, Condition for Destructive Interference, Interference of Sound Waves, Equation of Resultant Sound Wave after Interference & Quincke's Tube etc.

Important Questions on Interference of Sound Waves

EASY
IMPORTANT

Select the wrong statement about the phenomenon of interference?

MEDIUM
IMPORTANT

Find the amplitude of two sound waves of the same amplitude, each of 5.0 mm travelling  in the same direction. The phase difference between the waves is 60° and they interfere with each other. 

HARD
IMPORTANT

Deduce an expression for the resultant intensity after interference of two sound waves.

MEDIUM
IMPORTANT

What is the frequency of sound, when successive maximum and minimum of a sound were detected at a distance of  25 mm in  a Quincke's tube experiment.( the velocity of sound =340m/s )

 

MEDIUM
IMPORTANT

Describe the method of measuring the speed of sound by Quincke's tube.

MEDIUM
IMPORTANT

Describe the Quencke's tube

HARD
IMPORTANT

Two speakers connected to the same source of fixed frequency are placed 2 m apart in a box. A sensitive microphone placed at a distance of 4 m from their midpoint along the perpendicular bisector shows a maximum response. The box is slowly rotated until the speakers are in line with the microphone. The distance between the midpoint of the speakers and the microphone remains the same. Exactly five maximum responses are observed in the microphone in doing this. The wavelength of sound wave is (in m):

HARD
IMPORTANT

Two loudspeakers L1 and L2 driven by a common oscillator and amplifier are arranged as shown. The frequency of the oscillator is gradually increased from zero and the detector at D records a series of maxima and minima. If the speed of sound is 330 m s-1, then the frequency at which the first maximum is observed is

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MEDIUM
IMPORTANT

An observer receives waves directly from a source of sound distant 120 m in a big hall. He also receives waves reflected from the mid-point of 25 m high ceiling. The wavelength of sound for constructive interference to take place between two waves, must be

MEDIUM
IMPORTANT

Two speakers connected to the same source of fixed frequency are placed 2 m apart in a box. A sensitive microphone placed at a distance of 4 m from the mid-point along the perpendicular bisector shows maximum response. The box is slowly rotated till the speakers are in line with the microphone. The distance between the mid-point of the speakers and the microphone remains unchanged. Exactly 5 maximum responses (including the initial and last one) are observed in the microphone in doing this. The wavelength of the sound wave is,

MEDIUM
IMPORTANT

The loudspeakers L1 and L2 driven by a common oscillator and amplifier are set up as shown in the figure. As the frequency of the oscillator increases from zero, the detector at D recorded as a series of maximum and minimum signals. What is the frequency at which the first maximum is observed? (Speed of sound =330 m s-1)

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HARD
IMPORTANT

S1 & S2 are two coherent sources of sound having no initial phase difference. The velocity of sound is 330 m s-1. No minima will be formed on the line passing through S2 and perpendicular to the line joining S1 and S2 if the frequency of both the sources is

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MEDIUM
IMPORTANT

Figure shows a Young’s double slit experiment setup. The source S of wavelength 4000 oscillates along y- axis according to the equation y=sinπt, where y is in millimeters and t is in seconds. The distance between two slits S1 and S2 is 0.5mm.
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MEDIUM
IMPORTANT

Statement-1: Two sound waves of equal intensity I produced beats. The maximum intensity of sound produced in beats is 4I.

Statement-2: If two waves of amplitudes a1 and a2 superpose, the maximum amplitude of the resultant wave =a1+a2 .

HARD
IMPORTANT

2 loudspeakers are emitting sound waves of wavelength λ with an initial phase difference of π2. At what minimum distance from O on line AB will one hear maxima?

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MEDIUM
IMPORTANT

Two periodic waves of intensities I1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is

EASY
IMPORTANT

Three sources of equal intensities with frequencies 400, 401 and 402 vibrations per second are sounded together. The number of beats per second is

MEDIUM
IMPORTANT

Choose the correct statement

HARD
IMPORTANT

The two loudspeakers in the drawing are producing identical sound waves. The waves spread out and overlap at the point P. This situation is analogous to Young's double-slit experiment, except that sound waves are being used. What is the difference l2-l1 in the two path lengths, if point P is at the third sound intensity minimum from the central sound intensity maximum? Express this difference in terms of the wavelength λ  of the sound.

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MEDIUM
IMPORTANT

In Quincke's tube a detector detects minimum intensity. Now one of the tube is displaced by 5 cm. During displacement detector detects maximum intensity 10 times, then finally a minimum intensity (when displacement is complete). The wavelength of sound is :