Waves Questions for CBSE Class 11th

In a sound wave, to increase the intensity by a factor of 10, pressure amplitude must be changed by a factor of:

In the experiment for the determination of the speed of sound in air using the resonance column method, the length of the air column that resonates in the fundamental mode, with a tuning fork is 0.1 m. when this length is changed to 0.35 m, the same tuning fork resonates with the first overtone. Calculate the end correction

Three similar wires of frequency n 1 , n 2 and n 3 are joined to make one wire. Its frequency will be

The fundamental frequency of a closed pipe is 220Hz. If 1 4 of the pipe is filled with water, the frequency of the first overtone of the pipe now is

A transverse wave is propagating along +x direction. At t = 2 sec, the particle at x = 4 m is at y = 2 mm. With the passage of time its y coordinate increases and reaches to a maximum of 4 mm. The wave equation is(using at and k with their usual meanings)

The minimum intensity of sound is zero at a point due to two sources of nearly equal frequencies, when

The pipe closed at one end, has an air column. The air column is in resonance with a vibrating tuning fork of frequency f ( 75 Hz < f < 300 Hz ) . Length of air column is 93.75 cm. Find f (speed of sound in air is 330 m/s):

The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe L metre long. The length of the open pipe will be

A transverse wave described by equation y = 0 . 02 sin ( x + 30 t ) (where x and t are in metres and seconds, respectively) is travelling along a wire of area of cross-section I mm 2 and density 8000 kg / m 3 . What is the tension in the string?

An observer approaches towards a stationary source of sound at constant velocity and recedes away at the same speed. The graph of wavelength observed with time is:

The ratio of the maximum velocity of a particle to the velocity of wave is

The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe L metre long. The length of the open pipe will be

A sonometer wire is under tension of 64N vibrating in its fundamental mode is in resonance with a vibrating tuning fork. The vibrating portion of the sonometer wire has a length of 10cm and mass 1g. The vibrating tuning fork is now moved away from vibrating wire at a constant speed and an observer standing near the sonometer hears one beat per sec. Calculate the speed with which the tuning fork is moved, if the speed of sound in air is 300m/s.

A transverse wave is described by the equation y = y o sin 2 π ft – x λ .The maximum particle velocity is equal to four times the wave velocity if :

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

Two pipes have each of length 2 m. One is closed at one end and the other is open at both ends. The speed of sound in air is 340 m/s. The frequency at which both can resonate is ?

A tube, closed at one end and containing air, produces, when excited, the fundamental note of frequency 512 Hz. If the tube is opened at both ends the fundamental frequency that can be excited is (in Hz):

A man standing on a platform hears the sound of frequency 605 Hz coming from a frequency 550 Hz from a train whistle moving towards the platform. If the velocity of sound is 330 m/s, then what is the speed of train?

n waves are produced on a string in 1 s. When the radius of the string is doubled and the tension is maintained the same, the number of waves produced in 1 s for the same harmonic will be

When a source and observer move away from each other with equal speeds, which is 1/10th of the speed of sound, the apparent frequency received by the observer is n . If the source and observer move towards each other with same equal speeds as before, the apparent frequency received by the observer will be nearly

Two transverse sinusoidal waves travel in opposite directions along a string of length 3m whose both ends are fixed. The speed of transverse waves in the string is 0.5 cm/s. Each has an amplitude of 3 cm and wavelength of 6 cm. The equation for the resulting wave is

Statement I: Solids can support both longitudinal and transverse waves but only longitudinal waves can propagate in gases. Statement II: For the propagation of transverse waves’ medium must also necessarily have the property of rigidity.

Statement I: The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible. Statement II: Air is a bad conductor of heat and velocity of sound in air is large

The velocity of sound waves in air is 330 m./sec. For a particular sound in air, a path difference of 40 cm is equivalent to a phase difference of 1.6 π . The frequency of this wave is

Two identical piano wires kept under the same tension have a fundamental frequency of 600 Hz. The fractional increase in the tension of one of the wires which will lead to occurrence of 6 beat/s when both the wires oscillate together would be

The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is

If the frequency of a wave is increased by 25%, then the change in its wavelength will be: (medium not changed)

The pressure variation that correspond to pain threshold (i.e., the ear can tolerate in loud sound) is about 30 pa. Velocity of sound in water is 2 × 10 3 m/s. The intensity of sound wave produced in water corresponding to loud sound is

A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15 ms – 1 . Then. the frequency of sound that the observer hears in the echo reflected from the cliffis: (Take velocity of sound in air = 330 ms – 1 )

A sine wave of wavelength λ is travelling in a medium. The minimum distance between the two particles, always having same speed, is

Two waves having equations x 1 = asin ( ωt + φ 1 ) , x 2 = asin ( ωt + φ 2 ) If in the resultant wave the frequency and amplitude remain equal to those of superimposing waves. Then phase difference between them is

When a wave pulse travelling in a string is reflected from a rigid wall to which string is tied as shown in figure. For this situation two statements are given below. (l) The reflected pulse will be in same orientation of incident pulse due to a phase change of a π radians (2) During reflection the wall exert a force on string in upward direction For the above given two statements choose the correct option given below.

A string fixed at both ends has consecutive standing wave modes for which the distances between adjacent nodes are 18 cm and 16 cm respectively. The minimum possible length of the string is

When a stationary wave is formed then its frequency is

Two waves are approaching each other with a velocity of 20 m/s and frequency n. The distance between two consecutive nodes is

What is the percentage change in the tension necessary in a sonometer of fixed length to produce a note one octave lower (half of original frequency) than before?

Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed l0 m/s. If the minimum time interval between two instants when the string is flat is 0.5 s, the wavelength of the waves is

On producing the waves of frequency 1000 Hz in a Kundt’s tube, the total distance between 6 successive nodes is 85 cm. Speed of sound in the gas filled in the tube is

If amplitude of a wave is represented by A = c a + b – c then the resonance will occur when:

A man is standing on a railway platform listening to the whistle of an engine that passes the man at constant speed without stopping. If the engine passes the man at time t 0 . How does the frequency f of the whistle as heard by the man changes with time

A source of sound is moving with constant velocity of 20 m/s emitting a note of frequency 1000 Hz. The ratio of frequencies observed by a stationary observer while the source is approaching him and after it crosses him will be

A sinusoidal wave has an amplitude of 3cm. Time period is 1s. The wavelength is 1cm. And at x = 0, t=0 the particle is at its mean position & moving upwards. What is the equation of the wave if it is travelling along the positive x-axis?

When a wave travels in a medium, displacement of a particle is given by y = a sin ⁡ 2 π ( b t − c x ) where a, b and c are constants. The maximum particle velocity will be twice the wave velocity, if

If two anti-nodes are observed on either side of C, the frequency of the mode in which the rod is vibrating will be ( y = 2 × 10 11 N / m 2 , d = 8 × 10 3 kg / m 3 ) length of the rod is 2.5 m

A string fixed at both ends has consecutive standing wave modes for which the distances between adjacent nodes are 18 cm and 16 cm respectively. The minimum possible length of the string is

A source of unknown frequency gives 4 beats/s when sounded with a source of known frequency 250 Hz. The second harmonic of the source of unknown frequency gives five beats per second, when sounded with a source of frequency 513 Hz. The unknown frequency is

Three sound waves of equal amplitudes have frequencies (n-1), n,(n+1) . They superimpose to give beats. The number of beats produced per second will be

Two sources P and Q produce notes of frequency 660Hz each. A listener moves from P to Q with a speed of 1 m s – 1 . If the speed of sound is 330 m s – 1 , then the number of beats heard by the listener per second will be

A manometer connected to closed tap reads 3.5 × 10 5 N / m 2 . When the valve is opened , the reading of manometer falls to 3 × 10 5 N / m 2 , then velocity of flow of water is

Due to Doppler effect, the shift in wavelength observed is 0 . 1 A 0 , for a star producing a wavelength 6000 A 0 . The velocity of recession of the star will be :

The equation of a plane progressive wave is y = 0 . 09 sin 8 π t – x 20 . When it is reflected at rigid support, its amplitude becomes 2/3rd of its previous value. The equation of the reflected wave is

An organ pipe filled with oxygen gas at 47 0 C resonates in its fundamental mode at frequency 300Hz. If it is now filled with nitrogen gas, at what temperature will it resonate at the same frequency in the fundamental mode?

Which of the following is a mechanical wave ?

The displacement Vs time graph for two waves A and B which travel along the same string are shown in the figure. Their intensity ratio l A / l B is

The fundamental frequency of a string is proportional to

An open organ pipe is suddenly closed with the result that the second overtone of the closed pipe is found to be higher in frequency by 100 Hz than the first overtone of the original pipe. The fundamental frequency of open pipe will be

Two cars having velocities of 100 and 150 kPh are approaching each other. The frequency of a note emitted by the first as heard by its driver of the other is 1000 Hz. Speed of sound is 330 m/s. The two frequency of sound is

A transverse wave in a medium is described by the equation y = A sin ( a t- bx ) where a and b are constants. The maximum velocity of a particle of the medium will be four times the wave velocity, if the value of the product A× b is equal to

The frequency of a radar is 780 MHz. After getting re­flected from an approaching aeroplane, the apparent fre­quency is more than the actual frequency by 2.6 kHz. The aeroplane has a speed of

Three waves of equal frequencies having amplitudes 10 μm ,   4 μm   and   7 μm arrive of a given point. Phase difference between first and second wave is π 2 and that between second and third wave is π 2 . .Then amplitude of the resulting wave in μm ,is

A string of length 1m has the mass per unit length 0.1 gm/cm . Two ends of the string are attached to two rigid walls. A transverse vibration is set up in the string . A tension of 400 N is maintained in the string 2t the string oscillates in the first overtone and maximum displacement of a particle of the string is 2mm, the maximum velocity of a particle of the string is

Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed of 10 m/s. If the minimum time interval between two instants when the string is flat is 0.5 sec, the wavelength of the wave is

Fifth harmonic of an closed organ pipe matches with first overtone of an open organ pipe. Now the pipes are joined to form a closed organ pipe. Then the ratio of the fundamental frequency of the open pipe to that of the composite pipe is

Second overtone of a closed pipe is same as the second overtone of a open pipe. Then the ratio of first overtone of the closed pipe to the third overtone of the open pipe is

A source of unknown frequency produces 12 beats with a source of frequency 240 Hz, and 8 beats with another source of frequency 260 Hz. The unknown frequency will be

A police car is chasing a motorcyclist at a velocity of 20m/s. velocity of motor cyclist is 15m/s. Wind is blowing from the police car towards the motor cyclist with a velocity of 30m/s velocity of sound in still air is 330m/s. If the motor cyclist blows horn of frequency 400Hz, The apparent frequency of sound received by the police car is

A source of sound is allowed to fall freely from the top of a tower of height 20 m. A frequency detector is placed on the ground at the base of the tower. If the frequency of sound emitted by the source is 620 Hz, the apparent frequency recorded by the detector just before the source hits the ground is [velocity of sound in air = 330 m/s and g = 10 m / s 2 ]

Velocity of sound in hydrogen gas at 27 0 C    i s    V . Then what is the velocity of sound in helium gas at 127 0 C    ?

A transverse wave is described by the equation y = a sin 2 π f t − x λ . The maximum particle velocity is equal to four times the wave velocity if

A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of piano when tension in the wire of piano increased by 2% then beat frequency decreases by 2 beats per seconds, the frequency of piano string before increase in tension will be

The vibrations of a string of length 60 cm fixed at both ends are represented by y = 4 sin π x 15 cos 90 π t , where x and y are in cm and t is in second. Then velocity of component waves in the string is

The apparent frequency of the whistle of an engine changes in the ratio 3 : 2 as the engine passes a stationary observer. If the velocity of sound is 30 m/s, the velocity of the engine is

Statement I: On a rainy day sound travel slower than on a dry day. Statement II: When moisture is present in air the density of air increases.

Statement I: Sound produced by an open organ pipe is richer than the sound produced by a closed organ pipe. Statement II: Outside air can enter the pipe from both ends, in case of open organ pipe.

If in an experiment for determination of velocity of sound by resonance tube method using a tuning fork of 512 Hz, first resonance was observed at 30.7 cm and second was obtained at 63.2 cm, then maximum possible error in velocity of sound is (consider actual speed of sound in air is 332 m/s)

A wave packet with angular frequency ω 0 is propagating in dispersive medium with phase velocity of 1 . 5 × 10 3 m/s. When the frequency is increased by 2%, the phase velocity is found to decrease by 3%. What is the group velocity of the wave packet?

The string fixed at both ends has standing wave nodes for which distance between adjacent nodes is x 1 . The same string has another standing wave nodes for which distance between adjacent nodes is x 2 . If l is the length of the string, then x 2 x 1 = l ( l + 2 x 1 ) . What is the difference in numbers of the loops in the two cases?

A source of sound of requency 600 Hz is placed inside water. The speed of sound in water is 1500 m/s and in air is 300 m/s. The frequency of sound recorded by an observer who is standing in air is

Assertion: In a string wave, during reflection from fix boundary the reflected wave is inverted. Reason: The force on string by clamp is in downward direction while string is pulling the clamp in upward direction

Statement I: The fundamental frequency of an open organ pipe increases as the temperature is increased. Statement II: As the temperature increases, the velocity of sound increases more rapidly than length of the pipe.

Statement I: Transverse waves are not produced in liquids and gases. Statement II: Light waves are transverse waves.

Sinusoidal waves 5.00 cm in amplitude are to be transmitted along a string having a linear mass density equal to 4 . 00 × 10 – 2 kg / m . If the source can deliver a maximum power of 90 W and the string is under a tension of 100 N, then the highest frequency at which the source can operate is (take π 2 = 10 ):

Two sources of sound A and B produces the wave of 350 Hz, they vibrate in the same phase. The particle P is vibrating under the influence of these two waves, if the amplitudes at the point P produced by the two waves is 0.3 mm and 0.4 mm, then the resultant amplitude of the point P will be when AP – BP = 25 cm and the velocity of sound is 350 m/sec

Two interfering waves have intensities in the ratio 9:1. Then the ratio of maximum to minimum intensity is:

If we study the vibration of a pipe open at both ends, then the following statement is not true

Assertion: Transverse waves are not produced in liquids and gases. Reason: Light waves are transverse waves

A wave travelling in the +ve x-direction having displacement along y-direction as 1 m, wavelength 2 π m and frequency of 1 π Hz is represented by

A transverse wave is represented by y = A sin ( ωt – kx ) . For what value of the wavelength is the wave velocity equal to the maximum particle velocity?

Assertion: It is not possible to have interference between the waves produced by two violins. Reason: For interference of two waves the phase difference between the waves must remain constant

A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his retum joumey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train.B to that of train l is

Which two of the given transverse waves will give stationary waves when get superimposed? z 1 = acos ( kx – ωt ) ( A ) z 2 = acos ( kx + ωt ) ( B ) z 3 = a cos ( ky – ωt ) ( C )

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, then the speed of the component progressive wave is:

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, the frequency of the component progressive wave is:

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, the time period of the component progressive wave is:

Two vibrating strings of same length, same cross section area and stretched to same tension is made of materials with densities ρ and 2 ρ .Each string is fixed at both ends. If v 1 represents the fundamental mode of vibration of the one made with density ρ and v 2 for another, then v 1 v 2 is:

Two wires are kept tight between the same pair of supports. The tensions in the wires are in the ratio 2 : 1, the radii are in the ratio 3: 1 and the densities are in the ratio 1: 2. The ratio of their fundamental frequencies is

Two closed organ pipes, when sounded simultaneously gave 4 beats per sec. If longer pipe has a length of 1 m. Then length of shorter pipe will be, (v = 300 m/s)

An open pipe of length 33 cm resonates to a frequency of 1000 Hz. The mode of vibration is: (velocity of sound = 330 m/s)

A glass tube 1.5 m long and open at both ends, is immersed vertically in a water tank completely. A tuning fork of 660 Hz is vibrated and kept at the upper end of the tube and the tube is gradually raised out of water. The total number of resonances heard before the tube comes out of water, taking velocity of sound air 330 m/sec is

If the fundamental frequency of a pipe closed at one end is 512 Hz. The fundamental frequency of a pipe of the same dimensions but open at both ends will be:

An organ pipe of length L is open at one end and closed at other end. The wavelengths of the three lowest resonating frequencies that can be produced by this pipe are

In a resonance tube experiment, the first two resonances are observed at length 10.5 crn and 29.5 cm. The third resonance is observed at the length (cm).

A sound wave of frequency 500 Hz covers a distance of 1000 m in 5 second between the points X and Y. Then the number of waves between X and Y is:

Under similar conditions of temperature and pressure, in which of the following gases the velocity of sound will be largest?

In expressing sound intensity, we take 10 – 12 Wm – 2 , as the reference level. For ordinary conversation, the intensity level is about 10 – 6 Wm – 2 . Expressed in decibel, this is

Two passenger trains moving with a speed of 108 km/ hour cross each other. One of them blows a whistle whose frequency is 750 Hz. If speed of sound is 330 m/s, then after the trains cross each other, the passengers sitting in the other train will hear sound whose frequency will be

The displacement from the position of equilibrium of a point 4 cm from a source of sinusoidal oscillations is half the amplitude at the moment t = T 6 (T is the time period). Assume that the source was at mean position at t = 0. The wavelength of the running wave is:

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

Two identical wires are stretched by the same tension of 101 N and each emits a note of frequency 202 Hz. If the tension in one wire is increased by 1 N, then the beat frequency is:

A point source is emitting sound in all directions. The ratio of distance of two points from the point source where the difference in loudness levels is 3 dB is: ( log 10 2 = 0 . 3 )

A source of sound of frequency 256Hz is moving rapidly towards a wall with a velocity of 5m/s. The speed of sound is 330 m/s. If the observer is between the wall and the source, then beats per second heard will be

The sound intensity is 0.008 W / m 2 at a distance of 10 m from an isotropic point source of sound. The power of the source is:

A straight line source of sound of length L = l0 m, emits a pulse of sound that travels radially outward from the source. What sound energy (in mW) is intercepted by an acoustic cylindrical detector of surface area 2.4 cm 2 , located at a perpendicular distance 7 m from the source? The waves reach perpendicularly at the surface of the detector. The total power emitted by the source in the forrn of sound is 2 . 2 × 10 4 W . ( Use π = 22 7 )

A train is passing by a platform at a constant speed of 40 m/s. The train horn is sounded at a frequency of 378 Hz. Find the overall change in frequency as detected by a person standing on the platform, as the train moves from approaching to receding. (Take velocity of sound in air as 320 m/s)

The apparent frequency of a note, when a listener moves towards a stationary source, with velocity of 40 m/s is 200Hz. When he moves away from the same source with the same speed, the apparent frequency of the same note is 160 Hz. The velocity of sound in air is (in m/s)

A person is standing at a distance D from an isotropic point source of sound. He walks 50.0 m towards the source and observes that the intensity of the sound has doubled. His initial distance D from the source is

A string fixed at both ends resonates at a certain fundamental frequency. Which of the following adjustments would not affect the fundamental frequency?

A source of sound of frequency 600 Hz is placed inside water. The speed of sound in water is 1500 m/s and in air it is 300 m,/s. The frequency of sound recorded by an observer who is standing in air is

The displacement of a particle in a medium can be expressed as y = 10 − 6 sin ⁡ ( 100 t + 20 x + π / 4 ) metre, where t is in second and x in meter. The speed of the wave is

The Young’s modulus of the materials of the rod is, 2×10 11 N / m 2 and its density is 8000 kg/m 3 . The time taken by a sound wave to traverse 1 m of the rod will be

A is singing a note and simultaneously B is singing another note whose frequency is 1/8th that of A. The energy of two notes is the same. The amplitude of B note as compared to that of A note is

The correct graph between v 2 (square of the speed of sound) and absolute temperature T of the gas is

The graph between the pressure of a gas and speed of sound at constant temperate.re [fi8. (3)] is

Two sound waves of relative intensities 400 : 1 show interference. The ratio of intensity at the maxima to minima is close to

Two sources of intensities I and 4 I and waves, which interfere to produce a resultant intensity I o at a point of phase difference π / 2 . I 0 is equal to

The difference of sound levels between two points is 30 dB. The ratio of pressure amplitude between the two points is

The frequency of a train whistle is 360 Hz. As the train passes t}rough a station the frequency appears to be 400 Hz to a man who is standing on the station platform. If the speed of sound in air is 340 m/s, the speed of train is

The diameter of a wire stretched by a force of 144 N between two bridges distant 50 cm is 1 mm. It produces 4 beats with a tuning fork while vibrating in fundamental mode. On reducing the tension to 121 N, again 4 beats/sec are heard. The frequency of fork is

A rocket is going away from the earth at a speed of 10 6 m/s.If the wavelength of the light wave emitted by it be 5700 A, what will be its Doppler’s shift

The difference between the apparent frequency of a source of sound as perceived by the observer during its approach and recession is 2% of the natural frequency of the source. If the velocity of sound in air is 300 m/s, the velocity of the source is

The frequency of the sound of a car horn as perceived by an observer towards whom the car is moving differs from the frequency of the horn by 2.50/6. Assuming that the velocity of sound in air is 320 m/sec, the velocity of car is

The graph between the frequency n and square root of density (p) of a wire [Fig.(10], keeping its length radius and tension constant is

Two sound waves are y= α sin ( ω t-k x) and y = α = cos ( ω t-k x) . the phase difference between two waves is

An air column in a pipe, which is closed at one end, will be in resonance with a vibrating tuning fork of frequency 264 Hz if the length of the column in cm is given velocity of sound is equal to 332ms -1

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

Air is blown at the mouth of a tube (length 25 cm and diameter 3 cm) closed at one end. Velocity of sound is 330 m,/s. The sound which is produced will correspond to the frequencies

In a mixture of gases, the average number of freedom per molecule is 6. The r.m.s. speed of the molecules of the gas is C. The velocity of sound in the gas is

The apparent wavelength of light from a star moving away from the earth is 0.02% more than the actual wavelength.’What is the velocity of star ?

Two factories are sounding their sirens at 800 Hz. A man goes from one factory to the other at a speed of 2 m/s. The velocity of sound is 320 m/s. The number of beats heard by the person in one second will be

Two loudspeakers A and B, 1.0 m apart, produce sound waves of the same wavelength and in the same phase. A sensitive sound detector, moving along P Q parallel to line AB ,2.4 m away, detects maximum sound at P (on the perpendicular bisector of AB) and another maximum sound when it first reaches Q directly opposite to B as shown . The wvelength of sound emitted by the speakers is

Suppose that the speed of sound in air at a given temperature is 400 m/sec. An engine blows a whistle at 1200 Hz frequency. It is approaching an observer at the speed of 1oo m/sec. What is the apparent frequency as heard by the observer

The intensity in Wm -2 of a 70 d B noise is

Two harmonic waves traveling in the same medium have frequency ratio 1 : 2 and intensity ratio 1 : 36. Their amplitude ratio is

A string of length 10 0 m and mass 1.25kg is stretched with a tension of 50 N. If a transverse pulse is created at one end of the string, how Iong does it take to reach the other end ?

A jet plane passes over an aerodrome with a velocity 200 m/s at a height of 490 metre (see fig.). It constantly blows a whistle of 1 kHz. If it passes over the ground crew, in one second then the change in frequency observed by the staff in this interval will be (if velocity of sound v= 340 m/s)

Transverse waves are generated in two uniform wires A and B of same material by attaching their free ends to a vibrating source of frequency 200 Hz. The cross-sectional area A is half that of B, while the tension on A is twice that on B. The ratio of the wavelengths of the transverse waves in A and B is

A siren emitting sound of 1000 Hz is moving away from us towards a high hill with velocity 10 m/s. The frequency of sound reflected from the hill will be ( V = 330 m / s )

A sonometer wire vibrates with a frequency n. It is replaced by another wire of three times the diameter. If tension and other parameters remain the same, the frequency of vibration of the wire will be

The speed of longitudinal waves in a thin brass rod is 3480 m per second. If the rod is clamped at one end and gives a fundamental frequency of 435 Hz, the length of the rod is

A tuning fork of frequency of 500 c/s is sounded on a resonance tube. The first and second resonance are obtained at 17 cm and 52 cm. The velocity of sound in m/sec is

Two organ pipes, each closed at one end, give 5 beats per sec when emitting their fundamental notes. If their lengths are in the ratio of 50 : 51, their fundamental frequencies (in Hz) are

One end of a steel pipe of length 660 m is struck a blow. A listener at the other end hears two sounds at an interval of 1 .89 second, one through the metal and the other through air. If velocity of sound in air is 330 m/s, then velocity in metal will be

In a resonance tube, using a tuning fork of frequency 325 Hz, two successive resonance lengths are observed at 25. 4 cm and 77 . 4 cm respectively. The velocity of sound in air is

A pipe of length 1 m is closed at one end. The velocity of sound in air is 300 m/s. The air column in the pipe will not resonate for sound of frequency

The velocity of sound in air is v and the root mean square velocity of the molecules is c. Then v/c is equal to

If at same temperature and pressure the densities for two diatomic gases are respectively d 1 , and d 2 , then the ratio of velocity of sound in these gases will be

Given that threshold intensity of hearing at 1 kHz is 10 -12 W/m 2 , the density of air be 1.28 kg/m 3 and the speed of sound is 324 m/s. what is the pressure amplitude of the sound waves in air?

A bus is moving with a velocity of 5 m/s towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air = 335 m/s, the number of beats heard per second by a passenger on the bus will be

A source of sound S is moving with a velocity 50 m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him ? The velocity of sound in the medium is 350 m/s

A source of sound emits 200 π W power which is uniformly distributed over a sphere of 10 m radius. What is the loudness of sound on the surface of a sphere ?

A racing car moving towards a cliff sounds its horn. The driver observes that the sound reflected from the cliff has a pitch one octave higher than the actual sound of the horn. If v be the velocity of sound, the velocity of the car u is

A whistle emitting a sound of frequency 440 Hz is said to a string of 1 . 5 m length and rotated with an angular velocity of20 rad,/s in horizontal plane. Then the range of frequencies heard by an observer stationed at a large distance from the whistle will be (v = 330 m/s)

A band playing music at a frequency n is moving towards a wall at a speed v b . A motorist is following the band with a speed v m ,-. If v is the speed of sound, the expression for the beat frequency heard by the motorist is

Two sound sources emitting sound each of wavelength λ , are fixed at a given distance apart. A listener moves with a velocity v o along the line joining the two sources. The number of beats heard by him per second is

A person is observing two trains, one is approaching him with a velocity of 4 m/s while the other is receding from him with the same velocity. If both the taring blow their respective whistles of frequency 240 hearts, the beat frequency heard by the observer will be (speed of sound in air = 320 m/s)

A whistle revolves in a circle with angular speed ω = 20 rad /sec c using a string of length 50 cm. If the frequency of sound from the whistle is 385 Hz, then what is the minimum frequency heard by an observer which is far away from the center ⋅ v sound = 340 m / s .

A police car moving with velocity 22 m/s and emitting sound of frequency 176 Hz follows a motor-cyclist which in turn is moving towards a stationary car and away from the police car as shown in fig. [2). The stationary car is emitting a sound of frequency 165 Hz. If motor-cyclist does not hear any beat, then his velocity is

A radar sends a radio signal of frequency 9 x 10 9 Hz towards an aircraft approaching the radar. If the reflected wave shows a frequency shift of 3 x 10 3 Hz, the speed with which the aircraft is approaching the radar, in m/s is (velocity of the radio signal is 3 x 10 8 m/s

A uniform rod AB of length 0 . 4 m and mass 1 .2 kg is suspended by two identical wires from a ceiling as shown in fig. (3). Where should a mass of 4.8 kg be suspended from the rod so that a tuning fork of frequency 256 Hz is in resonance with the first wire at Awhile its first overtone resonates with second wire at B?

In the experiment for the determination of the speed of sound in air using the resonance column method, the length of the air column that resonates in the fundamental mode, with a tuning fork is 0 . 1m. When the length is changed to 0 .35 m, the same tuning fork resonates with the first overtone. The end correction is

Two wires are fixed in a sonometer. Their tensions are in the ratio 8 : 1. The lengths are in the ratio 36 : 35. The diameters are in the ratio 4 : 1. Densities of the materials are in the ratio 1 : 2. If the higher frequency in the setting is 360 Hz, the beat frequency when the two wires are sounded together is

The ends of a stretched wire of length tr are fixed at x =o and x = l. In one experiment, the displacement of the wire is y 1 =A sin ( π x/ L) sin ω t and energy is E 1 and in another experiment its displacement is y 2 =A sin,(2 π x L) sin 2 ω t and energy is E 2 . Then

A closed pipe of length / and an open pipe contain gases of densities ρ 1 and ρ 2 respectively. The compressibilities are equal in both the pipes. Both the pipes are vibrating in their first overtone with the same frequency. The length of the open organ pipe is

A racing car moving towards a cliff, sounds its horn. The driver observes that the sound reflected from the cliff has a pitch one octave higher than the actual sound of the horn. lf v is the velocity of sound, then the velocity of car is

The displacement y of a particle in a medium can be expressed as y = 10 − 6 sin ⁡ 100 t + 20 x + x 4 , where t is in second and x in metre. The speed of the wave is

A detector is released from rest under gravity over a source of sound of frequency f 0 = 10 3 H z . The frequency observed by the detector at time t is plotted in the graph. The speed of sound in air is ( g = 10 m / sec 2 ) :

An open pipe of sufficient length is dipping in water with a speed v vertically. If at any instant l is length of tube above water, then the rate at which fundamental frequency of pipe changes, is(speed of sound =c)

An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted are λ and f , respectively. The apparent frequency and wavelength recorded by the observer are respectively.

A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15 m s – 1 . Then, the frequency of sound that the observer hears in the echo reflected from the cliff is? (The Velocity of Sound in air = 330 m s – 1

Two plane progressive simple harmonic waves of same intensity move in same medium. If the amplitude ratio is 1 : 2, the wavelength ratio will be

A tuning fork is used to produce resonance in a glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of 27 0 C two successive resonances are produced at 20 cm and 73 cm of column length. If the frequency of the tuning fork is 320 Hz the velocity of sound in air at 27 0 C is

An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is 50cm. The next larger length of the column resonating with the same tuning fork is

If n 1 , n 2 a n d n 3 are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by

The number of possible natural oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are (Velocity of sound = 340 m s – 1 )

A speeding motorcyclist sees traffic jam ahead him. He slows down to 36 km hour – 1 . He finds that traffic has eased and a car moving ahead of him at 18 km hour – 1 is honking at a frequency of 1392 Hz. If the speed of sound is 343 m s – 1 , the frequency of the honk as heard by him will be

The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm the length of the open organ pipe is

A tuning fork of 512Hz is used to produce resonance in a resonance tube experiment. The level of water at first resonance is 30.7 cm and at second resonance is 63.2 cm. The error in calculating velocity of sound is (speed of sound in air = 330 m/s).

Two organ pipes both closed at one end, have lengths l and l + Δl . If the velocity of sound in air is ν , then the number of beats per second produced is :

A uniform rope of length L and mass m 1 hangs vertically from a rigid support. A block of mass m 2 is attached to the free end of the rope. A transverse pulse of wavelength λ 1 is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is λ 2 . The ratio λ 2 λ 1 is

A wave of frequency 100Hz is set along a string towards a fixed end. After reflection a node is formed at 10cm from the fixed end. The speed of the incident as reflected wave is

A stretched string of length 1m and mass 5 × 10 – 4 kg, fixed at both ends, is under a tension of 20 N. If it is plucked at points situated at 25 cm from one end, it would vibrate with a frequency :

A train is moving with a constant speed u along a circular track. A siren in its engine is emitting a sound of frequency v. If u = v/10, where v is the speed of sound, the apparent frequency of sound as heard by a passenger at the rear end of the train is

A string is stretched between fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 m s – 1 at an angle of 60° with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 m s – 1 , is

If we study the vibration of a pipe open at both ends, then the following statement is not true.

A wave travelling in the +ve x-direction having displacement along y-direction as 1 m, wavelength 2 π m and frequency of 1 π H z is represented by

A particle B executing S.H.M given by equation y = 8   sin 6 π t is sending out waves in a continuous medium travelling at 200 cm/sec. The resultant displacement of the particle 150 cms from B and one second after the commencement of vibration of B is

Speed of sound in air 332 m/sec at N.T.P. The speed of sound in hydrogen at N.T.P. will be

A table is revolving on its axis at 5 revolutions per second. A sound source of frequency 1000 Hz is fixed on the table at 70 cm from the axis. The minimum frequency heard by a listener standing at a distance from the table will be ( speed of sound = 352 m/sec)

Two waves approaching each other with a velocity of 20 m/s and frequency n. the distance between two consecutive nodes is

The length of the wire between two ends of a sonometer is 100 cm. What should be the positions of two bridges below the wire so that the three segments of the wire have their fundamental frequencies in the ratio 1: 3: 5.

The fundamental frequency of a closed organ pipe of length 20 cm is equal to the second overtone of an organ pipe open at both the ends. The length of organ pipe open at both the ends is

Two organ pipes, each closed at one end, give 5 beats per second when emitting their fundamental notes. If their lengths are in the ratio of 50 : 51, their fundamental frequencies (in Hz) are

A source of sound produces waves of wavelength 60 cm when it is stationary. If the speed of sound in air is 320 m s – 1 and source moves with speed 20 m s – 1 , the wavelength of sound in the forward direction will be nearest to

An equation of plane progressive wave y = a π sin 2 π 3   t − x b . If maximum velocity of particle and velocity of wave are equal. Now a b will be

Two sources A and B are sounding notes of frequency 680 Hz. A listener moves from A to B with a constant velocity u. If speed of sound is 340 m s – 1 , what should be the value of u so that he hears 10 beats/s ?

The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260Hz. What is the fundamental frequency of the system?

Two cars moving in opposite directions approach each other with speed of 22 m s – 1 and 16.5 m s – 1 respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340 m s – 1

In a guitar, two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz. when tension in B is slightly decreased, the beat frequency increases to 7 Hz. If the frequency of A is 530 Hz, the original frequency of B will be :

The length of the string of a musical instrument is 90 cm and has a fundamental frequency of 120 Hz. Where should it be pressed to produce fundamental frequency of 180 Hz?

A tuning fork of frequency 340Hz is vibrated just above a cylindrical tube of length 120cm. Water is slowly poured in the tube. If the speed of the sound in air is 340m/s the minimum height of the water required for resonance is

A transverse wave described by the equation y = 0.02 Sin ( x + 40 t ) ( where x and t are in metres and seconds respectively) is travelling along a wire of area of cross section 1 m m 2 and density 8000 k g / m 3 . What is the tension in the string?

A source and an observer are situated on two perpendicular tracks as shown in the figure. The observer is at rest and source is moving with a speed 50 m/s towards the observer. The source emits sound waves of frequency 90 Hz which travel in the medium with velocity 200 m/s. The frequency of sound heard by observer when the source crosses the origin O is

What would be the wavelength of a sound wave in iron (V = 4950 m/sec) if its wavelength was 1.4 m in air in which its speed was 330 m/sec.

In the experiment for the determination of the speed of sound in air using the resonance column, it is observed that 0.1 m of air column resonates with a tuning fork in the fundamental mode. When the length of the air column is changed to 0.35 m, the same tuning fork resonates with the first overtone. What is the end correction ?

A tuning fork with frequency 800 Hz produces resonance in a resonance column tube with upper end open and lower end closed by water surface. Successive resonance are observed at lengths 9.75 cm, 31.25 cm and 52.75 cm. The speed of sound in air is,

Two open organ pipes of fundamental frequencies n 1 and n 2 are joined in series. The fundamental frequency of the new pipe so obtained will be :

A metal rod of 1 m length, is dropped exact vertically on to a hard metal floor. With an oscilloscope, it is determined that the impact produces a longitudinal wave of 1.2 kHz frequency. The speed of sound in the metal rod is :

Two wires are fixed on a sonometer. Their tensions are in the ratio 8 : 1, their lengths are in the ratio 36 : 35, the diameters are in the ratio 4 : 1 and densities are in the ratio 1 : 2. Find the frequency of the beats produced if the note of the higher pitch has a frequency of 360 Hz.

A string of length l is fixed at both ends. It is vibrating in its 3 r d overtone with maximum amplitude ‘ a ’. Then wavelength of component waves is

The intensity level of a sound wave is 4 dB. If the intensity of the wave is doubled, then the intensity level of the sound wave would be [Given log 10 2 = 0.301 ]

A wire having a linear density of 0.10kg/m is kept under a tension of 490N. It is observed that it resonates at a frequency of 400Hz and the next higher frequency is 450Hz. The length of the wire is

N incoherent sources of intensity I 0 are super imposed at a point, The intensity of the point is

A transverse wave travels along the Z–axis. The particles of the medium must move

Longitudinal waves cannot

Consider ten identical sources of sound all giving the same frequency but having phase angles which are random. If the average intensity of each source is I 0 . The average resultant intensity I due to all these ten sources will be

The bulk modulus and the density of water are greater than those of air. With this much of information, we can say that velocity of sound in air

The speed of sound in a medium depends on

When you speak to your friend, which of the following parameters have a unique value in the sound produced ?

An open organ pipe of length L vibrates in its fundamental mode. The pressure variation is maximum

An organ pipe, open at both ends, contains

The displacement of particles in a string stretched in the x-direction is represented by y. Wave equation is described by :

A wave pulse on a string has the dimension shown in figure. The wave speed is v = 1 cm/s. If point O is a free end. The shape of wave at time t = 3 s is :

Tuning fork A of frequency 258 Hz gives 8 beats with a tuning fork B. When prongs of B are cut and again A and B are sounded together , the number of beats heard remains same. The frequency of B in Hz is

When a tangential force of 0.02 N is applied on a large wooden plate of area 10 m 2 floating on the surface of the river, plate moves with the speed of 2 m/s on the river surface. If the river is 1 m deep and the water in contact with the bed is stationary, The coefficient of viscosity of water is

Two persons A and B are on a horizontal ground at a separation of 60m. Person A is blowing a whistle at a frequency of 252 Hz and at the same time he is moving towards B with a velocity of 8.5 m/s. If velocity of sound in air is 340 m/s, the wavelength of sound wave received by B

Equations of a stationary and a travelling waves are as follows y 1 = a sin kx cos ωt and y 2 = a sin ωt – Kx The phase difference between two points x 1 = π 3 k and x 2 = 3 π 3 k are ϕ 1 and ϕ 2 respectively for the two waves. The ratio ϕ 1 ϕ 2 is

In a sine wave position, of different particles at time t = 0 is shown in the figure. The equation for this wave if it is travelling along positive x–axis can be

Velocity of transverse wave in a stretched string is ‘V’ when elongation produced in it is ‘x’, what will be the velocity of transverse wave in the same string when elongation produced in it is ‘2x’ ?

The time taken by sound waves to travel the distance l if the air temperature between them varies linearly from T 1 to T 2 (velocity of sound in air is given by v = α T )

Two waves are represented by y 1 = 5 sin 2 π ( 75 t – 0 . 25 x ) y 2 = 10 sin 2 π ( 150 t – 0 . 50 x ) The intensity ratio l 1 l 2 of the two waves is

If two waves of the same frequency and same amplitude on superposition produce a resultant disturbances of same amplitude the waves differ in phase by

The equation for the vibration of a string fixed at both ends vibrating in its third harmonic is given by y   =   2 c m   sin 0 .6 cm − 1   x   cos 500 πs − 1   t   The length of the string is :

A string is under tension so that its length is increased by 1 n times its original length. The ratio of fundamental frequency of longitudinal vibrations and transverse vibrations will be :

When sound wave is refracted from air to water, which of the following will remain unchanged?

A small source of sound moves on a circle as shown in figure and an observer is sitting at O. Let ν 1 , ν 2 , ν 3 be the frequencies heard when the source is at A, B and C respectively

A source of sound moves towards an observer.

The speed of a wave in a certain medium is 960 m/s. If 3600 waves pass over a certain point of the medium in 1 min, the wavelength is

The linear density of a vibrating string is 10 – 4 kg/m. A transverse wave is propagating on the string, which is described by the equation y = 0.02 sin (x + 30 t), where x and y are in metres and time t in seconds. Then tension in the string is

A source of sound produces waves of wavelength 60 cm when it is stationary. If the speed of sound in air is 320 m/s and source moves with speed 20 m/s, the wavelength of sound in the forward direction will be nearest to

The equation of the propagating wave is y = 25 sin (20t + 5x), where y is displacement. Which of the following statements is not true?

Consider the standing wave, y = A sin π x 30 sin 2 π t where x is in cm and t is in second. Phase difference (in radians) between two particles at x=25 cm and 35 cm is

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?

A bus moving away from a wall with a speed of 10 m/s blows siren at frequency 680 Hz. If speed of sound in air is 330 m/s, the frequency heard by driver of bus is

A pipe open at both ends has fundamental frequency f 1 . When 3 4 t h of its length is in water, it produces fundamental note of f 2 . Then f 2 f 1 is

The frequency of B is 3% greater than that of A. The frequency of C is 2% less than that of A. If B and C produce 8 beats/s, then the frequency of A is

A standing wave having 3 nodes and 2 antinodes is formed two atoms having a distance of 1.21Å between them. The wavelength of standing wave is

A car is moving towards a high cliff. The driver sounds a horn of frequency f. The reflected sound heard by the driver has a frequency 2 f. If v be the velocity of sound, then the velocity of the car, in the same velocity units would be

For a certain organ pipe, three successive resonance frequencies are observed at 425, 595 and 765 Hz. The speed of sound in air is 340 m/s. The pipe is a

Length of a closed pipe is 75 cm. First overtone of this closed pipe beats with the first over tone of an open pipe with a beat frequency of 5 Hz. If velocity of sound in air is 330 Hz, what is the length of the open pipe ?

Two sources of sound S 1     and     S 2 are at some distance apart. A person is at some point between S 1     and     S 2 on the line joining them. Each of the sources emits sound with frequency f 0 . The source S 1 starts moving away from the person with velocity v n and the source S 2 starts moving towards the listener with velocity v n . If velocity of sound in air is V, find the beat frequency heard by the person.

A transverse wave on a stretched string is represented by the equation y = 0.4    sin 60 t − 20 x , where x is in metre and t is in second. It linear mass density of the wire is 16   ×   10 − 3   k g / m , the tension in the string is

A source of sound approaches an observer and the apparent frequency of sound heard by the observer is f. When the source remains stationary and the observer approaches the source with same velocity apparent frequency heard by the observer is 15 f 16 . If velocity of sound in air is 330 m/s, velocity of source is

A train is moving towards a stationary observer at a constant speed, i s blowing a horn at frequency f 0   continuously . Which of the following curve best represents the frequency f received by observer as a function of time t ?

On a stretched string fixed at both ends, three possible wave lengths that can be generated are 90 cm, 60 cm and 45 cm. The length of the string may be

An observer is moving with speed v 0 towards a stationary source emitting a sound wave of wavelength λ The change in wavelength detected by the observer is (v = speed of sound)

A nuclear bomb exploded 200 km above the surface of moon.The sound of explosion on the moon

A long string is lying along X-axis and a tension is maintained in it. Linear mass density is gradually increasing along positive X-axis. A transverse wave is propagating along the string in positive X direction. Then

The phase difference between velocity and acceleration of a particle in simple harmonic motion

Frequency of transverse oscillations of a taut string fixed at both ends is same as that of a tuning fork and when they oscillate together, beats of frequency 5 Hz are produced. If the tension in the string is slightly decreased the beat frequency is increased to 8 Hz. If frequency of the tuning fork is 450 Hz, what is the original frequency of the string?

A stationary wave is set up in a string whose two ends are attached to two rigid walls and a tension is maintained in the string. Then

A car is moving towards a stationary observer with a velocity of 16 m/s and at the same time blowing horn at a frequency of 300 Hz. If velocity of sound in air is 320 m/s, the wavelength of sound wave received by the observer is

Equation of transverse wave propagating in a string having linear mass density 10 gm/m is y = 0.5   sin 100 π t − 2.5 π x , where x is m metre, y is in mm and t is in second. Then tension in the string is

Two open end organ pipes of lengths 50 cm and 50.5 cm produce 3 beats/s. Then velocity of sound in air is (The air columns are oscillating in fundamental mode)

Statement I: Compression and rarefaction involve changes in density and pressure. Statement II: When particles are compressed, density of medium increases and when they are rarefied, density of medium decreases.

Statement I: Sound would travel faster on a hot summer day than on a cold winter day. Statement II: Velocity of sound is directly proportional to the square of its absolute temperature.

Statement I: When we start filling an empty bucket with water, the pitch of sound produced goes on decreasing. Statement II: The frequency of man’s voice is usually higher than that of woman

Statement I: The speed of sound in solids is maximum though their density is larger than liquid. Statement II: The coefficient of elasticity of solid is large.

Statement I: It is not possible to have interference between the waves produced by two violins. Statement II: For interference of two waves the phase difference between the waves must remain constant.

A closed organ pipe of length L and an open organ pipe contain gases of densities ρ 1 and ρ 2 respectively. The compressibility of gases are equal in both the pipes. Both the pipes are vibrating in their first overtone with same frequency. The length of the open organ pipe is

A transverse wave is described by the equation Y = Y o sin 2 π ( ft – x λ ) . The maximum particle velocity is four times the wave velocity if

A wave equation which gives the displacement along the direction Y is given by the equation y = 10 4 sin ( 60 t + 2 x ) , where x and y are in metres and t is time in seconds. This represents a wave

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?

A source of sound S is moving with a velocity of 50 m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him? The velocity of the sound in the medium is 350 m/s.

When a string is divided into three segments of length l 1 , l 2 a n d l 3 the fundamental frequencies of these three segments are f 1 , f 2 and f 3 respectively. The original fundamental frequency (f) of the string is

The ends of a stretched wire of length L are fixed at x = 0 and x = L. ln one experiment, the displacement of the wire is y 1 = A sin ( πx L ) and energy is E 1 , and in another experiment its displacement is y 2 = A sin ( 2 πx L ) sin 2 ωt and energy is E 2 . Then

The ratio of the speed of sound in nitrogen gas to that in helium gas, at 300 K is

A whistle giving out 450 Hz approaches a stationary observer at a speed of 33 m/s. The frequency heard by the observer in Hz is

The displacement y of a particle in a medium can be expressed as : y = 10 – 6 sin [ 100 t + 20 x + π 4 ] m , where t is in second and x in meter. The speed of wave is

The displacement y of a wave travelling in the x-direction is given by y = 10 – 4 sin ( 600 t – 2 x + π 3 ) metres, where x is expressed in metres and t in seconds. The speed of the wave-motion in ms – 1 , is

Tube A has both ends open while tube B has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube A and B is

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

Statement I: In the case of a stationary wave, a person hear a loud sound at the nodes as compared to the antinodes. Statement II: In a stationary wave all the panicles of the medium vibrate in phase.

Statement I: The velocity of sound increases with increase in humidity. Statement II: Velocity of sound does not depend upon the medium.

When temperature increases, the frequency of a tuning fork

The displacement of a particle in a string carrying a travelling wave is represented by the equation y = A sin Kx – ω t + ϕ . At t = 0, The particle at x = 0 is at half of amplitude and is moving in upward direction. Then value of ϕ is

A pipe, which is closed at one end has a length of 1m. Neglecting end correction, the air column in the pipe can resonate for the sound of frequency velocity of sound in air is 320m/s

The string of length L is stretched by x when the speed of transverse wave along it is V 1 . The string is further stretched by ∆ x when the speed of transverse wave along it is V 1 2 . Find ∆ x:

The equation of a transverse wave travelling on a rope is given by y = 10 sinπ ( 0 . 01 x – 2 . 00 t ) where y and x are in cm and t in seconds. The maximum transverse speed of a particle in the rope is about

A transverse wave is passing through a stretched string with a speed of 20 m/s. The tension in the string is 20 N. At a certain point P on the string, it is observed that energy is being transferred at a rate of 40 mW at a given instant. Find the speed of point P.

Two waves are propagating to the point P along a straight line produced by two sources A and B of simple harmonic and of equal frequency. The amplitude of every wave at P is ‘a’ and the phase of A is ahead by π 3 than that of B and the distance AP is greater than BP by 50 cm. Then the resultant amplitude at the point P will be, if the wavelength is 1 meter

Equation of motion of two waves in the same direction is given by y 1 = A sin ( ωt – kx ) , y 2 = A sin ( ωt – kx – θ ) . The amplitude of the particle of the medium will be

The amplitude of a wave at an instant is represented by displacement equation y = 1 a sin ωt ± 1 b cosωt will be

A wave travelling in positive X-direction with A = 0.2 m has a velocity of 360 m/sec if λ = 60 m, then correct expression for the wave is

A sine wave of wavelengh λ is travelling in a medium. The minimum distance between the two particles, always having same speed, is

A transverse periodic wave on a string with a linear mass density of 0.200 kg/m is described by the following equation y = 0 . 05 sin ( 420 t – 21 . 0 x ) where x and y are in metres and t is in seconds. The tension in the string is equal to

There are 10 sound sources each producing intensity I, at a point independently. They are incoherent. Average intensity of sound at that point will be:

Two coherent sources of different intensities send waves which interfere. The ratio of the maximum intensity to the minimum intensity is 25. The intensities are in the ratio:

A wave represented by the given equation y = a cos ( kx – ωt ) is superposed with another wave to form a stationary wave such that the point x = 0 is a node. The equation for the other wave is

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 n 1 and the other with frequency n 2 . The ratio n 1 n 2 , is given by

A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is f 1 . If the train’s speed is reduced to 17 m/s, the frequency registered is f 2 . If the speed of sound is 340 m/s then the ratio f 1 f 2 is

Assertion: In a stationary wave, there is no transfer of energy. Reason: There is no outward motion of the disturbance from one particle to adjoing particle in a stationary wave.

A whistle emitting a sound of frequency 440 Hz is tied to a string of 1.5 m length and rotated with an angular velocity of 20 rad/sec in the horizontal plane. Then the range of frequencies heard by an observer stationed at a large distance from the whistle will (v = 330 m/s):

Assertion: The fundamental frequency of an open organ pipe increases as the temperature is increased. Reason: As the temperature increases, the velocity of sound increases more rapidly than length of the pipe.

If n 1 , n 2 and n 3 , are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 ms – 1 at an angle of 60° with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 ms – 1 ) is

A train moving at a speed of 220 ms – 1 towards a stationary object emits a sound of frequency 1000 Hz. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is (speed of sound in air is 330 ms – 1 )

A uniform rope of length L and mass m 1 hangs vertically from a rigid support. A block of mass m 2 is attached to the free end of the rope. A transverse pulse of wavelength λ 1 is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is λ 2 . The ratio λ 2 λ 1 is

An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is 50 cm. The next larger length of the column resonating with the same tuning fork is:

A string is stretched between fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is

A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2 m/s one second after it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be: (given that velocity of sound = 300 m/s; g = l0 m / s 2 )

A wire is stretched between two rigid supports. It is observed that wire resonates at the frequencies f 1 , f 2 , f 3 and f 4 ( f 4 > f 3 > f 2 > f 1 ) forming 2,3,4 and 5 loops respectively. The ratio of any two resonance frequencies will be minimum for difference in the loops to be:

Two monoatomic ideal gases 1 and 2 of molecular masses m 1 and m 2 respectively are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas 1 to that in gas 2 is given by is given by

Two travelling waves y 1 = A sin [ k ( x – ct ) ] and y 2 = A sin [ k ( x + ct ) ] are superimposed on string. The distance between adjacent nodes is

A metal wire of linear mass density of 9.8 g/m is stretched with a tension of 10 kg weight between two rigid supports 1 metre apart. The wire passes at its middle point between the poles of a permanent magnet, and it vibrates in resonance when carrying an alternating current of frequency n. The frequency n of the alternating source is

Length of a string tied to two rigid supports is 40 cm. Maximum length (wavelength in cm) of a stationary wave produced on it is

Which of the following curves represents correctly the oscillation given by y = y 0 sin ( ωt – φ ) , where 0 < φ < 90 0 ?

A wave motion has the function y = a 0 sin ( ωt – kx ) . The graph in figure shows how the displacement y at a fixed point varies with time l. Which one of the labelled points shows a displacement equal to that at the position x = π 2 k at time t = 0?

The same progressive wave is represented by two graphs I and II. Graph I shows how the displacement ‘y’ varies with the distance x along the wave at a given time. Graph II shows how y varies with time t at a given point on the wave. The ratio of measurements AB to CD, marked on the curves, represents:

The displacement-time graphs for two sound waves A and B are shown in the figure, then the ratio of their intensities I A I B is equal to

A travelling wave y = A sin ( kx – ωt + θ ) passes from a heavier string to a lighter string. The reflected wave has amplitude 0.5 A. The junction of the strings is at x = 0. The equation of the reflected wave is:

Two pulses are traveling along a string in opposite directions towards each other as shown in the figure. If the wave velocity is 2 cm/s and the pulses are 6 cm apart, then after 1.5 sec, the energy stored in the string will be (Assume shapes of pulses to be similar)

At a certain instant a stationary transverse wave is found to have maximum kinetic energy. The appearance of string at that instant is

In a stationary wave all the particles

A transverse wave is represented by the equation y = y 0 sin 2 π λ ( vt – x ) For what value of λ , the maximum particle velocity equal to two times the wave velocity?

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, then the amplitude of progressive wave is:

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time / in second, then the wavelength of the component progressive wave.

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, the separation between two consecutive antinodes is:

The equation of a stationary wave is given by y = 6 sin ( πx 3 ) cos 40 πt where y and x are given in cm and time t in second, then the phase difference between two points on opposite sides of an antinode with a separation of I cm between them is:

A tuning fork vibrating with a sonometer having 20 cm wire produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to 21 cm. the frequency of the tuning fork (in Hertz) must be

A second harmonic has to be generated in a string of length l stretched between two rigid supports. The point where the string has to be plucked and touched are

Four wires of identical lengths, diameters and materials are stretched on a sonometer box. The ratio of their tensions is 1:4:9:16. The ratio of their fundamental frequencies is

In order to double the frequency of the fundamental note emitted by a stretched string, the length is reduced to 3 4 th of the original length and the tension is changed. The factor by which the tension is to be changed is

A guitar string of length L has a fundamental frequency. Where should it be pressed to produced another fundamental frequency, if the ratio of two fundamental frequencies is f?

The first overtone of a stretched string of given length is 320 Hz. The first harmonic is

A string of 7 m length has a mass of 0.035 kg. If tension in the string is 60.5 N, then speed of a wave on the string is

A wire of length l having tension T and radius r vibrates with fundamental frequency f. Another wire of the same metal with length 2l having tension 2T and radius 2 r will vibrate with fundamental frequency:

A wire having a linear mass density 5.0 x 10 – 3 kg/m is stretched between two rigid supports with a tension of 450 N. The wire resonates at a frequency of 420 Hz. The next higher frequency at which the same wire resonates is 480 Hz. The length of the wire is

What is the base frequency if a pipe gives notes of frequencies 425, 255 and 595 and decide whether it is closed at one end or open at both ends?

In a resonance pipe the first and second resonances are obtained at depths 22.7 cm and 70.2 cm respectively. What will be the end correction?

An open organ pipe of length L resonates at fundamental frequency with closed organ pipe. Find the length of closed organ pipe.

An open pipe is suddenly closed with the result that the second overtone of the closed pipe is observed to be higher in frequency by 100 Hz than the first overtone of the original pipe. The fundamental frequency of the open pipe will be

A closed organ pipe has length ‘ l ‘. The air in it is vibrating in 3rd overtone with rnaximum amplitude ‘a’. The amplitude at a distance of l 7 from closed end of the pipe.

The velocity of sound in a gas at temperature 27°C is V then in the same gas its velocity will be 2V at temperature:

Propagation of a sound wave in a gas is quite close to

A sound wave of frequency 440 Hz is passing through air. An O 2 molecule (mass = 5.3 x 10 – 26 kg) is set in oscillation with an amplitude of 10 – 8 m speed at the centre of its oscillation is:

The frequency of a man’s voice is 300 Hz and its wavelength is 1 meter. If the wavelength of a child’s voice is 1.5 m, then the frequency of the child’s voice is:

The graph between the ( velocity ) 2 and temperature T of a gas is

Figure shown is a graph, at a certain time t, of the displacement function S(x, t) of three sound waves 1, 2 and 3 as marked on the curves that travel along x-axis through air. If P 1 , P 2 and P 3 represent their pressure amplitudes respectively, then correct relation between them is:

The average density of Earth’s crust 10 km beneath the surface is 2.7 gm/ cm 3 . The speed of longitudinal seismic waves at that depth is 5.4 km/s. The bulk modulus of Earth’s crust considering its behavior as fluid at that depth, is:

Two identical sounds S 1 and S 2 reach at a point P in phase. The resultant loudness at point P is n dB higher than the loudness of S 1 . The value of n is:

For a sound source of intensity I W / m 2 , corresponding sound level is Bo decibel. If the intensity is increased to 4I, new sound level becomes:

A two-fold increase in intensity of a wave implies an increase of (Given: log 10 2 = 0 . 3010 .)

Sound waves are emitted uniformly in all directions from a point source. The dependence of sound level β in decibels on the distance r can be expressed as (a and b are positive constants)

A person is talking in a small room and the sound intensity level is 60 dB everywhere within the room. If there are eight people talking simultaneously in the room, what is the sound intensity level?

A point source of power 50 π watts is producing sound waves of frequency 1875 Hz. The velocity of sound is 330m/s, atmospheric pressure is 1 . 0 × 10 5 Nm – 2 , density of air is 1.0 kg m – 3 . Then pressure amplitude at , r = 330 m from the point source is (using π = 22 7 ):

A point source of power 50 π watts is producing sound waves of frequency 1875 Hz. The velocity of sound is 330 m/s, atmospheric pressure is 1 . 0 × 10 5 Pa , density of air is 400 99 π kgm – 3 . Then the displacement amplitude at r = 330 m from the point source is

The faintest sound, the human ear can detect at a frequency of 1 kHz (for which ear is most sensitive) corresponds to an intensity of about 10 – 12 w / m 2 . Assuming the density of air = 1.5 kg / m 3 and velocity of sound in air ≅ 300 m/s, the pressure amplitude and displacement amplitude of the sound will be respectively N / m 2 and m.

An observer starts moving with uniform acceleration a towards a stationary sound source emitting a whistle of frequency n. As the observer approaches source, the apparent frequency, heard by the observer varies with time as

When a sound wave is reflected from a wall, the phase difference between the reflected and incident pressure wave is:

A curve is plotted to represent the dependence of the ratio of the received frequency f to the frequency f 0 emitted by the source on the ratio of the speed of observer V ob to the speed of sound V sound in a situation in which an observer is moving towards a stationary sound source. The curve is best represented by:

With what velocity an observer should move relative to a stationary source so that he hears a sound of double the frequency of source?

A table is revolving on its axis at 5 revolutions per second. A sound source of frequency 1000 Hz is flxed on the table at 70 cm from the axis. The minimum frequency heard by a listener standing at a distance from the table will be (speed of sound = 352 m/s)

An observer standing at station observes frequency 219 Hz when a train approaches and 184 Hz when train goes away from him. If velocity of sound in air is 340 m/s, then velocity of train and actual frequency of whistle will be

A small source of sound moves on a circle as shown in the figure and an observer is standing on O. Let n 1 , n 2 and n 3 be the frequencies heard when the source is at A, B and C respectively. Then

The difference between the apparent frequency of a source of sound as perceived by an observer during its approach and recession is 2% of the natural frequency of the source. lf the velocity of sound in air is 300 m/sec, the velocity of the source is (It is given that velocity of source << velocity of sound)

Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of 72 km/hr and 36 km/hr. If first car blows horn of frequency 280 Hz, then the frequency of horn heard by the driver of second car when line joining the cars make 45° angle with the roads; will be

A stationary observer receives sonic oscillations from two tuning forks, one of which approaches and the other recedes with same speed. As this takes place the observer hears the beat frequency of 2 Hz. Find the speed of each tuning fork, if their oscillation frequency is 680 Hz and the velocity of sound in air is 340 m/s. [Use g = 10 m / s 2 ]

At each of two stations A and B, a siren is sounding with a constant frequency of 250 cycle s – 1 . A cyclist from A proceeds straight towards B with a velocity of 12 km h – 1 and hears 5 beats/s. The velocity of sound is nearly:

A wall is moving with constant velocity u towards a fixed source of sound of frequency ‘f .The velocity of sound is ‘v’. The wavelength of the sound reflected by the wall is

A sounding body emitting a frequency of 150 Hz is dropped from a height. During its fall under gravity it crosses a balloon moving upwards with a constant velocity of 2 m/s one second after it started to fall. The difference in the frequency observed by the man in balloon just before and just after crossing the body will be: (given that velocity of sound = 300 m/s; g = 10 m / s 2 )

A sonometer wire is vibrating with a frequency of 30 Hz in the fundamental mode. If the length of the wire is increased by 20%, the change in frequency of the fundamental mode is

A source of sound moves towards an observer. What happens to the speed of sound in the medium?

Two interfering waves have a frequency of 202 Hz & 206 Hz. What is the beat frequency?

Equation of sound wave propagating in still air is y = a sin ωt − Kx . Then the equation of pressure wave propagating in the same medium is of the form

A sinusoidal sound wave is propagating in still air. At an instant of time displacement of a particle from its mean position is y , acceleration of the particle is a and velocity of propagation is v . Then

A transeverse wave is propagating in a string in which a tension is maintained. A, B, C and D are four particles of the string. Then select the correct option.

A sinusoidal transverse wave is propagating in a string in which a tension is maintained. Then, potential energy stored per unit length is maximum at point

Equation of a transverse progressive wave in a string is y = 5 sin 400 πt − 20 πx mm where x is in meter and t in second. If the mass of the string is 0.1 kg/m, then the tension in the string is

Equation of a transeverse wave propagating in a string is y = 2 sin 50 πt − 10 πx mm . Where x is in metre. If at t = 0, elastic potential energy stored in the string at x = 10/4 cm is 2 J/m, what is the elastic potential energy stored in the string at x = 10/3 cm?

Two ends of a string are tied to two rigid walls and the string is oscillating transeversely with maximum amplitude ‘A’ in the first overtone mode. The total energy of oscillation of the string is 0.32 J. If the same string oscillates with maximum amplitude A/2 in the second overtone mode, its total energy of oscillation will be

A string of uniform cross-sectional area is suspended from one of its ends. A transverse pulse is produced at its lower end and the pulse starts propagating up the string. Then the acceleration of the pulse is (Take g = 10 m/s 2 )

Two ends of a thin string AB are tied to two rigid walls and it is oscillating transversely in the fundamental mode. Then

Two ends of a string AB are attached to two rigid walls. The string is oscillating transeversely in its first overtone. When the string is passing through its equilibrium position kinetic energy of an element of the string.

The correct graph between the frequency f and square root of density ρ of the material of a string keeping its length, radius and tension constant, is

Change in velocity of sound in a gas per degree rise in temperature at 27 o C is ‘x’. Then change in velocity of sound per degree rise in temperature in the same gas at 127 o C will be

A string of length 120 cm, fixed at both ends, is vibrating in three segments with frequency 30 Hz. Then velocity of propagation of component waves in the string is

A string of uniform cross-sectional area is hanging from one of tis ends as shown in figure. A transverse sinusoidal pulse is generated at the lower end and the pulse is propagating up the string. If the wavelength of wave at the mid-point C is λ , what is the wavelength at the uppermost point A?

‘A’ sings with frequency ‘n’ and ‘B’ sings with a frequency ‘n/4’. If the energy remains the same and the amplitude of ‘A’ is ‘a’, then amplitude of ‘B’ is

The ends of two identical strings are tied to two rigid walls and same tension is maintained in them. The strings are oscillating in their fundamental made with frequency 100 Hz. If the tension in one of them is increased by 6%, then frequency of beats is

Three waves represented by y 1 = 10 sin 50 πt − 0 .252 mm   y 2 = 4 cos 50 πt − 0 .25   x mm and y 3 = 7 sin 50 πt − 0 .25   x + π mm arrive at a given point. Then the resultant wave is represented by

A closed pipe of length 22 cm, when excited by a 1875 Hz source forms standing waves. The number of pressure nodes formed in the pipe are (velocity of sound in air = 330 m/sec )

Two sinusoidal waves of same amplitude of 1 cm propagate in opposite directions along x-axis. Wavelength of each wave is 6 cm speed of each wave is 0.5 cm/s. Then at any time t, displacement of a particle from its equilibrium position is zero at

String of a sonometer of length 48 cm between bridges vibrate in second overtone. Then amplitude of vibration is maximum at a distance x from one bridge. Then x is

A police car moving at 22 ms − 1 , chases a motorcyclist. The police man sounds his hom at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. Calculate the speed of the motorcycle, if it is given that he does not observes any beats [speed of sound 330   ms − 1 ]

Two trains A and B are moving in the same direction with velocities 30 m / s and 10 m / s respectively. B is behind from A and A blows a horn of frequency 450 Hz. Then the apparent frequency heard by observer on train B is (speed of sound is 330 m/s):

An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer?

A vehicle, with a horn of frequency n, is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency n + n 1 . Then, n 1 is equal to: (take velocity of sound in air as 330 m/s):

If the ratio of intensities of two waves causing interference be 9 4, then the ratio of the resultant maximum and minimum intensities will be :

Two graphs of the same harmonic wave are shown below. The graph (1) on the left shows the displacement of wave y, as a function of position x for a given instant of time. The graph ( 2 ) on the right shows the displacement of wave as a function of time ‘t’ for a given position. The speed of the wave is

Two coherent sources of different intensities send waves which interfere. If the ratio of maximum and minimum intensity in the interference pattern is 25 then find ratio of intensities of sources:

A train blowing its whistle is moving with uniform speed along a straight track. The variation in the apparent frequency f of the whistle with time t as the train passes by an observer standing near the track is best represented by:

The equation y = 0.15 sin 5x cos 300 t represents a stationary wave. The wavelength of this stationary wave will be

A stretched string of length l fixed at both ends can sustain stationary waves of wavelength given by –

Under similar condition of temperature and pressure, which of the following will have the least velocity of sound?

The mass of a 4 m wire is 0.01 kg and it is stretched by a force of 400 N. What is the speed of transverse wave in the wire?

A stretched string of 1 m length, fixed at both ends, having a mass of 5 x 10 – 4 kg is under a tension of 20 N. It is plucked at a point situated at 25 cm from one end. The stretched string would vibrate with a frequency of-

In Melde’s experiments in the longitudinal mode of vibration a string vibrates in 4 loops with a load of 8 gm. How much load would be required in order that the string many vibrate in 8 loops in transverse mode.

In a resonance tube experiment a student using a tuning fork vibrating at frequency 800 Hz produces resonance in a resonance column tube. The upper end is open and the lower end is closed by the water surface which can be changed. Successive resonances are observed at lengths 9.75 cm, 31.25 cm and 52.75 cm. the approximate speed of sound in air from this data will be?

A wave is represented by the equation y = Asin ⁡ ( 10 πx + 15 πt + π / 3 ) where x is in metre and t is in second. The expression represents

The equation of a transverse wave is given by y = 10 sin ⁡ π ( 0 ⋅ 01 x − 2 t ) where y and x are in cm and t is in sec.Its frequency is

The displacement y (in cm) produced by a simple harmonic wave is given by y = ( 10 / π ) sin ⁡ ( 2000 πt − πx / 17 ) The periodic time and maximum velocity of the particles in the medium will respectively be

A wave is represented by the equation y = 7 sin ⁡ ( 7 πt − 0 ⋅ 04 x + π / 3 ) where x is in metre and t in second. The speed of the wave is

The equation of a wave traveling in a string can be written as y=3 cos π (100-x) Its wavelength is

A transverse wave is described by the equation Y = Y 0 sin ⁡ 2 π ( ft − x / λ ) The maximum particle velocity is equal to four times the wave velocity if

Velocity of sound is measured in hydrogen and oxygen gases at a given temperature. The ratio of two velocities will be V H / V O

The velocity of sound in oxygen at 30 o C is 330 m/sec Therefore the velocity of sound in m/sec in helium at the same temperate is

The speed of sound in a gas is v and root mean square speed of gas molecules is V rms ∗ If the ratio of specific heats of the gas γ = 1 ⋅ 5 , then the ratio V / V rms is

The speed of sound in hydrogen at N.T.P. is 1270 metre per second. Then the speed in a mixture of hydrogen and oxygen containing hydrogen and oxygen in the ratio 4 : 1 by volume, will be

Disturbances of two waves are shown as a function of time in fig. (+). The ratio of their intensities will be

A wave represented by the equation y = acos ⁡ ( kx − ωt ) is superposed with another wave to from a stationary wave such that the point x=0 is a node. The equation for the other wave is

If the intensity of sound is doubled, the intensity level will increase by

A tuning fork of frequency 250 Hz is vibrating at one end of a tube as shown in fig. (6). If maximum sound is heard at the other end, the velocity of wave will be

If the sound emitted by a point source reaches a particular position with an intensity I, then the change in intransigent level at that position if N such sources are placed together is

A sound source is moving towards a stationary observer with a speed equal to 1/10 th of the speed of sound. The ratio of apparent to real frequency is

A source of frequency 512 c.p.s. moves towards a listener with a speed.of 100 m/sec. If the velocity of sound in ah is 350 m/sec, the frequency heard by listener is

A man is watching two trains, one leaving and the other coming in, with equal speed of 4 m/s. If they sound their whistles, each of natural frequency of 240 Hz the number of beats heard by the man (velocity of sound in air = 320 m/s) will be equal to

At what speed should a source of sound move so that observer finds the apparent frequency equal to half of the original frequency ?

Two persons A and B each carrying a source.of sound of frequency n, are standing a few meters apart in a quiet field. A starts moving towards B with a speed v 0 . If v be the speed of sound, the number of beats heard per second by A will be

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 ?

Two sources A and B are sounding notes of frequency 680 Hz. A listener moves from A to B with a constant velocity u. If the speed of sound is 340 m/s, what must be the value of u so that he hears 1 0 beats per second ?

A table is rotating about its axis at the rate of 5 rotations per second. A source of sound of frequency 10 3 Hz is fixed at a distance 0 . 7 m from its axis. If the velocity of sound is 352 m/s, then the difference of apparent frequencies heard by an observer standing in front of the table, will be

A stationary source S produces sound of frequency 500 Hz which is heard by stationary observer. Now a Large reflector is placed behind the source which moves with a speed of 1 m/s towards the source. The number of beats heard per second by the observer will be

The frequency of a radar is 780 MHz. The frequency of the reflected wave from an aeroplane is increased by 2 .6 kHz. The velocity of aeroplane is

A rocket is going towards moon with a speed v. The astronaut in the rocket sends signals of frequency n towards the moon and receives them back on reflection from the moon. What will be the frequency of the signal received by the astronaut ? (Take v < <c)

A wire under tension vibrates with a frequency of 450 per second. What would be the fundamental frequency if the wire were half as long, twice as thick and under one-fourth tension

A stretched string of length / fixed at both ends can sustain stationary waves of wavelength λ Given by

A uniform metal wire of density p, cross-sectional area A and length i is stretched with a tension T. The speed of transverse wave in the wire is given by

In brass the velocity of longitudinal wave is 100 times the velocity of the transverse wave. If Y = 1 × 10 11 N / m 2 then stress in the wire is

A string oscillating at fundamental frequency under a tension of 225 N produces 6 beats per second with a sonometer. If the tension is 256 N, then again oscillating at fundamental note it produces 6 beats per second with the same sonometer. What is the frequency of the sonometer ?

In Melde’s experiment, the string vibrates in 7 segments under tension of 9 gm-wt. If the string is to be vibrated in 3 segments, then the tension required will be

If two waves of same frequency and same amplitude respectively, on superposition produce a resultant disturbance of the same amplitude, the waves differ in phase by

When a body of mass 25 kg is suspended from a sonometer wire, then it vibrates with frequency 200 Hz. If the volume of the body is 0’009 m3 and it is immersed in water, then the frequency of vibrating of the wire will be

A sonometer wire with a suspended mass of M =1kg is in resonance with a given tuning fork The apparatus is taken to the moon where the acceleration due to gravity is 1/6 that on the earth. To obtain resonance on the moon, the value of M should be

Two parts of a sonometer wire divided by a movable bridge differ in length by o ‘ 2 cm and produce one beat per second, when sounded together. The total lengths of wire is one metre, then the frequencies are

Transverse waves are generated in two uniform steel wires A and B by attachilg their free end to vibrating source of frequency 500 Hz. The diameter of wire A is half that of wire B and the tension on wire A is half that on wire B. What is ratio of the velocity of waves in wires A and B?

A stretched string of 1 m length, fixed at both ends, having amass of 5 x 10 -4 kg is under tension of 20 N It is plucked at a point situated at 25 cm from one end. The stretchered string would vibrate with a frequency of

A piano wire having a diameter of 0 .90 mm is replaced by another wire of the same material but with a diameter0 .93mm. If the tension of the wire is kept the same, then the percentage change in the frequency of the fundamental tone is

Two identical straight wires are stretched so as to produce 6 beats per second when vibrating simultaneously. On changing the tension slightly in one of them, the beat frequency remains unchanged. Denoting by T 1 , and T 2 , the higher and lower initial tensions in the strings, then it could be said that while making the above changes in tension

A wire of density p is stretched between two clamps a distance L apart, while being subjected to an extension I.Y is the Young’s modulus of the material of the wire. The lowest frequency of transverse vibration of the wire is given by wire is given by

A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of a piano. The beat frequency decreases to z beats per second when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was

A string is stretched between fixed points separated by 75 . 0 cm. It is observed to have resonant frequencies of 42O Hz and. 315 Hz. There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is

A tuning fork of frequency n is held near the open end of a tube which is closed at the other end and the length of the tube is adjusted until resonance occurs. If the two shortest lengths that produce resonance are ,l 1 and 1 2 , the speed of the sound is

An organ pipe P 1 , closed at one end vibrating in its first harmonic and another pipe P 2 , open at both ends vibrating in its third harmonic are in resonance with a given tuning fork. The ratio of the length of p 1 to that of P 2 , is

An organ pipe of effective length 0 . 6 m is closed at one end. Given that the speed of the sound in air is 300 m/sec, the two lowest frequencies for the pipe are

An open pipe is suddenly closed with the result that, the second overtone of the closed pipe is found to be higher in frequency by 100 Hz, then the first overtone of the original pipe. The fundamental frequency of open pipe will be

A closed organ pipe of length L and an open organ pipe contain gases of densities ρ 1 and ρ 2 , respectively. The compressibility of gases are equal. in both the pipes. Both the pipes are vibrating in their first overtone with same frequency. The length of the open organ pipe is

A sound absorber attenuates the sound level by 20 dB The intensity decreases by a factor of

A transverse wave is represented by the equation y = y 0 sin ⁡ 2 π λ ( vt − x ) For what value of λ is the particle velocity equal to two times the wave velocity ?

The equation y = acos 2 ⁡ ( 2 πnt − 2 πx / λ ) represents a wave with

The velocities of sound in an ideal gas at temperature T 1 , and T 2 , K are found to be V 1 , and V 2 , respectively. If the root mean square speeds of the same gas at the same temperatures. T 1 and T 2 , are v 1 , and v 2 , respectively, then

Two monatomic ideal gases 1 and 2 of molecular masses m 1 and m 2 , respectively are enclosed in separate containers kept at same temperature. The ratio of the speed of sound in gas 1 to that in gas 2 is given by

The power of a sound from the speaker of a radio is 20 mW. By turning the knob of the volume control, the power of the sound is increased to 400 mW. The power increase in decibels as compared to the original power

A source of sound of frequency 256 Hz is moving towards a wall with a velocity of 5 m/s. Velocity of sound is 330 m/s. The number of beats heard by an observer standing behind the source is nearly

A train moves towards a stationary observer with a speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is f 1 . If the train’s speed is reduced to 17 m/s the frequency registered is f 2 . If the speed of sound is 340 m/s then the ratio f 1 / f 2 is

A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is

A disc of radius .R is rotating uniformly with angular frequency o A source of sound is fixed to the rim of the disc. The ratio of maximum and minimum frequencies heard by stationary observer, far away from the disc and in the plane of the disc is (v = speed of round)

A small source of sound moves on a circle with constant speed as shown in fig. (1) and an observer is sitting on O. Let v 1 v 2 and v 3 v 1 ,v 2 and v 3 , be the frequencies heard when the source is at A, B and C respectively, then

A source of sound of frequency 500 Hz is fixed to the end of a light string and is whirled in a vertical circle of radius 1 . 6 m. The string just remains taut when the source is at the highest point. An observer is located at a large distance, in the same vertical plane and at the same height of the vertical circle. Find the maximum apparent frequency heard by the observer if the velocity of sound in air is 330 m,/sec

In a resonance column experiment, the first resonance is obtained when the level of the water in the tube is at 20 cm from the open end. Resonance will also be obtained when the water level is at a distance of

A wave frequency 100 Hz is sent along a string towards a fixed end. When this wave travels back after reflection. a node is formed at a distance of 1O cm from the fixed end of the string. The speeds of incident (and reflected) wave are

A tube is closed at one end and the other end is closed by a vibrating diaphragm which may be assumed to be a displacement anti node. It is found that when the frequency of the diaphragm is 2000 Hz a stationary wave pattern is set up in the tube and the distance between adjacent nodes is 8 cm. When the frequency is gradually reduced the stationary wave pattern disappears, but another stationary wave pattern appears at a frequency 1600 Hz. Calculate the length of the tube between diaphragm and closed end

Two wires of same material and of same length are stretched between two fixed supports. Wire,{ is thicker than wire B. If the initial tensions are same (T A =T B ) and temperature increases

A transverse wave described by equation y = 0.2 sin (x+30t) (where x and t are in metre and second) is travelling along a wire of cross-sectional area 1 mm 2 and density 8000 kg/m 3 . what is the tension in the string ?

A load of 20 kg is suspended by a steel wire. Its frequency when rubbed with a resined cloth is found to be 20 times its frequency when plucked. If y of the wire is 19 .6 x 1o1r dyne/square cm, what is its area of cross-section ?

Two vibrating strings of the same material but lengths L and 2 L have radii 2.r and r respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length I with frequency n, and the other with frequency n 2 . The ratio n 1 , / n 2 , is given by

Two pulses in a stretched string whose centres are initially 8 cm apart are moving towards each other as shown in fig. (a). The speed of each pulse is 2 cm/s. After 2 second, the total energy of the pulses will be

A sonometer wire resonates with a given tuning fork forming standing waves with five antinodes between the two bridges when a mass of 9 kg.is suspended from the wire. When this mass is replaced by a mass M, the wire resonates with the same tuning fork forming three antinodes for the same positions of the bridges. The value of M is

Two uniform strings, A and B made of steel are made to vibrate under the same tension. Radius of A is two times the radius of B . If the first overtone of A is equal to the second overtone of B, the ratio of lengths of the string is

Two uniform wires are vibrating simultaneously in their fundamental nodes. The tensions, lengths, diameters and densities of two wires are in the ratio I : 1, 36 : 35, 4 : 1 and 1 : 2 respectively. If the note of the higher pitch has a frequency 360 Hz, the number of beats produced per second is

In a resonance tube experiment to determine the speed of sound in air, a pipe of diameter 5 cm is used. The air column in pipe resonates with a tuning fork of frequency 480 Hz when the minimum length of air column is 16 cm. The speed of sound in air at room temperature is

Two stars P and Q are observed at night. Star P appears reddish white while star Q as white. From this, we conclude

What is the phase difference at a given instant of time between two particles 25 m apart, when the wave y ( x , t ) = 0.03 sin ⁡ π ( 2 t − 0.01 x ) travels in a medium?

The frequency of a sound wave is n and its velocity is ν . If the frequency is increased to 4 n , the velocity of the wave will be