wave motions questions

Wave Motion Questions: Paper – 01

1.

If x a sin and x’ a cos t, then what is the phase difference between the two waves(RAJ PMT-96)

(a)

(b)

(c) (d) Answer: (a)

2. When a sound wave of frequency 300 Hz passes through a medium, the maximum displacement of a particle of the medium is 0.1 cm. the maximum velocity of the particle is equal to (MNR-92)(a) 60 cm/s (b) 30 cm/s(c) 30 cm/s (d) 60 cm/sAnswer: (a)

3. Two tuning forks A and B vibrating simultaneously produce 5 beats. Frequency of B is 512 Hz. It is seen that if one arm of a is filed, then the number of beats increases. Frequency of A will be (PMTMP-91)(a) 502 Hz (b) 507 Hz(c) 517 Hz (d) 522 HzAnswer: (c)

4. A simple harmonic wave having amplitude A and time period T is represented by the equation y 5 sin(t 4) metres. Then the value of A (in metres) and T (in seconds) are (MNR-91)(a) A 5, T 2(b) A 10, T 1(c) A 5, T 1(d) A 10, T 2Answer: (a)

5. Which one of the following cannot represent a traveling wave(NCERT-84)(a) y f (x t)(b) y ym sin k (x t)(c) y ym log (x t)(d) y f (x2 t2)Answer: (c)

6. Which of the following statements is wrong(NCERT-76)(a) Sound travels in a straight line (b) Sound travels as waves(c) Sound is a from of energy (d) Sound travels faster in vacuum that then in airAnswer: (d)

7. The equation of a progressive wave traveling on a stretched string is y 10

sin where x and y are in cm and t is in sec. what is the speed of

the wave?(a) 500 cm/s (b) 50 m/s(c) 40 m/s (d) 400 cm/sAnswer: (b)

8. When a compression is incident on rigid wall it is reflected as (MHT-CET 2006)(a) Compression with a phase change of (b) Compression with no phase change(c) Rarefaction with a phase change of (d) Rarefaction with no phase changeAnswer: (a)

9. The wavelength of sound in air is 10 cm. its frequency is, (Given velocity of sound 330 m/s) (CPMT-74)(a) 330 cycles per second (b) 3.3 kilo cycles per second(c) 30 mega-cycles per second (d) 3 × 105 cycles per secondAnswer: (b)

10 Two waves are represented by

y1 a sin and y2 a cos t. what will be their resultant amplitude? (RAJ PMT-96)(a) a(b) (c) (d) 2 aAnswer: (c)

11 Sound waves having the following frequencies are audible to human beings (CPMT-75)(a) 5 c/s (b) 27000 c/s(c) 5000 c/s (d) 50,000 c/sAnswer: (c)

12 A sound wave is represented byy a sin (1000t 3x). the distance between two points having a phase difference of 60 is(MHT CET 2003)

(a)

(b)

(c)

(d) Answer: (c)

13 The equation of wave traveling along string is y 3 cos (100t x) in C.G.S. unit then wavelength is(CPMT-91, MPPMT-94,97, MNR-85)(a) 1 m (b) 2 cm(c) 5 cm

(d) None of aboveAnswer: (b)

14 A siren emitting a note of frequency n is fitted on a police van, traveling towards a stationary listener. What is the velocity of the van, if the frequency of he note heard by the listener is double the original frequency?(a) VS V

(b) (c) VS 2V

(d) Answer: (b)

15 In the longitudinal waves the direction of vibration in medium of particle is (MHT-CET 2005)(a) Perpendicular to propagation of wave (b) Parallel to propagation(c) Different from each other (d) Variable for time to time.Answer: (b)

16 The relation between frequency n, wavelength and velocity of a wave is (CPMT 76, 85)(a) n (b) n

(c)

(d) Answer: (b)

17 With the propagation of a longitudinal wave through a material medium the quantities transmitted in the propagation direction are(CBSE-92)(a) Energy, momentum and mass (b) Energy(c) Energy and mass (d) Energy and linear momentumAnswer: (d)

18 A wave is represented by the equation

y A sin (10x 15t ), where x is in meters and t is in seconds. The expression represents (IIT-90)(a) A wave traveling in the positive x-direction with a velocity 1.5

m/s (b) A wave traveling the negative x-direction with a velocity 1.5 m/s(c) A wave traveling in the negative x-direction have a wave-length 0.2

m (d) Both ‘b’ and ‘c’Answer: (d)

19 Loudness of a note of sound is (MHT-CET 99)(a) Directly proportional to amplitude of the wave (b) Directly proportional to square of amplitude of wave(c) Directly proportional to velocity of the wave (d) Directly proportional to square of velocity of the waveAnswer: (b)

20 The velocity of sound is maximum in (AFMC Pune 98)(a) Water (b) Air(c) Vacuum

(d) MetalAnswer: (d)

21 A wave is represented by the equation

y 7 sin , where x is in meters and t is in seconds. The speed of the wave is,(a) 175 m/s (b) (49 ) m/s(c) (49 / ) m/s(d) (0.28 ) m/sAnswer: (a)

22 Two wave having the intensities in the ratio of 9: 1 produce interference. The ratio of maximum to minimum intensity is equal to(MNR-87)(a) 10 : 8 (b) 9 : 1(c) 4 : 1 (d) 2 : 1Answer: (c)

23 Two tuning forks of frequencies 256 and 258 vibrations/second are sounded together. Then the time interval between two consecutive maxima heard by an observer is (PMT - MP-88)(a) 2 sec (b) 0.5 sec(c) 250 sec (d) 252 secAnswer: (b)

24 Two waves are y1 0.25 sin 316t,y2 0.25 sin 310t are traveling in same direction. The number of beats produced per second will be(CPMT-93)(a) 6(b) 3

(c) (d) 3Answer: (c)

25 What is phase difference between two successive troughs in the transverse wave?

(a) (b)

(c) (d) 2Answer: (d)


1. A transverse wave given by y 2 sin (0.01x 30t) moves on a stretched string from one end to another end is 0.5 sec. if x and y are in cm and t is in sec, then the length of the string is(a) 6 m(b) 9 m(c) 12 m(d) 15 m

Answer: (d)2. Two waves are represented by

x1 A sin and x2 A cos t, then the pase difference between them is

(a)

(b)

(c) (d) Answer: (c)

3. The displacement y (in cm) produced by a simple harmonic wave is given by

the periodic time and maximum velocity o the particles in the medium will respectively be (CPMT-86)(a) 103 sec and 330 m/s(b) 104 sec and 20 m/s(c) 103 sec and 200 m/s(d) 102 sec and 2000 cm/s.Answer: (c)

4. Two sound waves are given byy a sin (t kx) and y’ b cos (t kx). The phase difference between the two waves is (EAMCET-89)

(a)

(b) (c)

(d) Answer: (a)

5. The equation of a progressive wave is given by,

y 5 sin m, then the frequency of the wave is(a) 100 Hz(b) 50 Hz(c) 25 Hz(d) 10 HzAnswer: (c)

6. If V is the velocity of the wave and is the angular velocity, then the propagation constant (K) of the wave is given by

(a)

(b) (c) K 2n

(d) Answer: (b)

7. Two sounding bodies producing progressive wave given by y1 4 sin 400 t and y2 4 sin 404 t are situated very near to the ears of a person who will hear(CPMT-88)(a) 2 beats per second with intensity ratio (4/3) between maxima and

minima(b) 2 beats per second with intensity ratio (49/1) between maxima

and minima(c) 4 beats per second with intensity ratio (7/1) between maxima and

minima(d) 4 beats per second with intensity ratio (4/3) between maxima and

minimaAnswer: (b)

8. 56 tuning forks are so arranged in series, that each fork gives 4 beats/second with the previous one. If the frequency of the last fork is 3 times that of the first, then the frequency of the first fork will be(a) 55 Hz(b) 110 Hz(c) 75 Hz(d) 220 HzAnswer: (b)

9. The speed of sound in air at N.T.P. is 300 m/s. if air pressure becomes four times, then the speed of sound will be (NCERT-73, CPMT-91)(a) 150 m/s(b) 300 m/s(c) 600 m/s(d) 1200 m/sAnswer: (b)

10 Two sound waves having a phase difference of 60 have path difference of (CBSE 96)(a) 2

(b)

(c)

(d) Answer: (c)

11 The velocity of sound is measured in hydrogen and oxygen at a certain temperature. The ratio of the velocities is, (CPMT-76)(a) 1:1(b) 1:2(c) 1:4(d) 4:1Answer: (d)

12 Consider the following statements:Assertion A : The velocity of sound in the air increases due to presence of moisture in itReason (R) : The presence of moisture in air lowers the density of air. Of these statements (SCRA-94)(a) Both (A) and (R) are true and (R) is the correct explanation of (A)(b) Both (A) and (R) are true but (R) is not the correct explanation of (a)(c) (A) is true but (R) is false(d) (A) is false but (R) is trueAnswer: (a)

13 If the amplitude of waves at a distance r from a line source is A, then

. amplitude at a distance 4 r will be:(a) 2A(b) A

(c)

(d) Answer: (d)

14 The equation of a progressive wave traveling on a string is y 4

sin cm. the velocity of the wave is (MPPMT-90)(a) 64 cm/s along x direction.(b) 64 cm/s along x direction.

(c) cm/s along x direction

(d) cm/s along x directionAnswer: (c)

15 What is the phase difference between two successive crest in the wave? (MHT CET 2004)(a)

(b) (c) 2(d) 4Answer: (c)

16 If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will be (CBSE-92)(a) Increasing by a factor of 2(b) Decreasing by a factor of 2(c) Decreasing by a factor of 4(d) UnchangedAnswer: (c)

17 Which of the following expressions is that of a simple harmonic progressive wave (CPMT-75)(a) a sin t(b) a sin (t) cos (kx)(c) a sin (t kx)(d) a cos kxAnswer: (c)

18 Frequency of tuning forks are 320 Hz. And 325 Hz. If they are sounded together, the beat period is…….(MHT CET 2003)(a) 5 second(b) 6 second(c) 0 second(d) 0.2 secondAnswer: (d)

19 A wave equation which gives the displacement along the Y direction is given by y 104 sin(60t 2x), where x and y are in metres and t is time in seconds. This represents a wave (MNR-83, IIT-82)(a) Traveling with a velocity of 30 m/s in the negative x direction(b) Of wavelength x metre

(c) Of frequency hertz.(d) All of the aboveAnswer: (d)

20 Equation of progressive wave is given by

y 4 sin then which of he following is correct?(CBSE 93)(a) 5 cm(b) 18 m(c) a 0.04 m(d) f 50 HzAnswer: (b)

21 The velocity of sound in any gas depends upon(CBSE-92)(a) Wavelength of sound only(b) Density and elasticity of gas(c) Intensity of sound waves only(d) Amplitude and frequency of soundAnswer: (b)

22 The amplitude of two waves are in the ratio 5:2. if all other conditions for the two waves are same, then what is the ratio of their energy densities? (MHT-CET 2004)(a) 5 : 2(b) 10 : 4(c) 2.5 : 4(d) 25 :4Answer: (d)

23 Ultrasonic waves are those waves(CPMT-79, NMR-83)(a) To which man can hear(b) Man can not hear(c) Are of high velocity(d) Of high amplitudeAnswer: (b)

24 The velocity of sound in air at 4 atmosphere and that at 1 atmosphere pressure would be (CPMT-79)(a) 1 : 1(b) 4 : 1(c) 1 : 4(d) 3 : 1Answer: (a)

25 To demonstrate the phenomenon of beats we need(a) Two sources which emit radiation of nearly the same frequency(b) Two sources which emit radiation of exactly the same frequency(c) Two sources which emit radiation of exactly the same frequency

and have a definite phase relationship(d) Two sources which emit radiation of exactly the same wavelengthAnswer: (a)


1. A tuning fork of frequency 480 Hz. Produces 10 beats per second when sounded with a vibrating sonometer string. What must have been the frequency of the string if a slight increase in tension produces fewer beats per seconds then before? (PMT-92, NCERT-84)(a) 460 Hz (b) 470 Hz(c) 480 Hz (d) 490 HzAnswer: (b)

2. A whistle giving out 450 Hz approaches a stationery observer at a speed of 33 m/s. the frequency heard by the observer in Hz is (velocity of sound 330 m/s)(MHT CET 2001)(a) 409 (b) 429(c) 517 (d) 500Answer: (d)

3. When a source is going away from a stationary observer, with a velocity equal to that of sound in air, then the frequency heard by the observer will be(a) Same (b) Half(c) Double (d) One thirdAnswer: (b)

4. A wave travels in a medium according to the equation of displacement given byy(x,t) 0.03 sin (2t 0.01x), where y and x are in meters and ‘t’ is seconds. The wavelength of the wave is (EAMCET-94)(a) 200 m (b) 100 m(c) 20 m (d) 10 mAnswer: (a)

5. Ten tuning fork are arranged in increasing order of frequency in such a way that any two nearest tuning forks produce 4 beats per second. The highest frequency is twice that of the lowest. Possible highest and lowest frequencies are(PMT - MP-90, MHT-CET 2002)(a) 80 & 40 (b) 100 & 50(c) 44 & 22 (d) 72 & 36Answer: (d)

6. The equation of a wave is given byy 10 sin (0.01 x 2t) where y and x are in cm and t is in sec. its frequency is (MNR-86)(a) 10 sec1 (b) 2 sec1

(c) 1 sec1 (d) 0.01 sec1

Answer: (c)7. Velocity of sound in air is (CPMT-79)

(a) 300 m/s (b) 3.8 1010 m/s(c) 3 108 m/s(d) 9 1019 m/s

Answer: (a)8. If the pressure amplitude in a sound wave is tripled. Then by what

factor the intensity of the sound wave increased (CPMT-92)(a) 3(b) 6(c) 9(d) Answer: (c)

9. A tuning fork X produces 4 beats/sec with a tuning fork Y of frequency 384 Hz. When the prongs of X are slightly filed, 3 beats/sec are heard. What is the original frequency of X?(a) 388 Hz (b) 381 Hz(c) 380 Hz (d) 387 HzAnswer: (c)

10 Which of the following phenomenon cannot take place with sound wave? (CPMT 85)(a) Reflection (b) Interference(c) Diffraction (d) PolarizationAnswer: (d)

11 The velocity of sound in vacuum is, (PEN 84, MP)(a) Zero (b) 27.5 m/s(c) 156 m/s (d) 330 m/sAnswer: (d)

12 The equation of a plan progressive wave is given byy 0.025 sin (100t 0.25x). The frequency wave would be

(a) (b) 100 Hz

(c) (d) 50 HzAnswer: (a)

13 The fork A of frequency 100 Hz is sounded with an other tuning fork B. the number of beats produced is 2. on putting some wax on the prong of B. the number of beats reduces to 1. the frequency of the fork B is(NCERT-77)(a) 101 Hz (b) 99 Hz(c) 102 Hz (d) 98 HzAnswer: (c)

14 In a sinusoidal wave, the time required by a particular particle to move from maximum displacement to zero displacement is 0.025 sec. the frequency of the wave is(a) 2.5 Hz (b) 5 Hz(c) 7.5 Hz (d) 10 HzAnswer: (d)

15 Transverse waves can propagate (CPMT 84)(a) In a gas but not in a metal (b) In a metal but not in gas(c) Neither in a gas nor in a metal (d) Either in a gas or in a metalAnswer: (b)

16 Velocity of sound waves in air is 330 m/s. for a particular sound in air, a path difference of 40 cm is equivalent to a phase difference of 1.6. The frequency of the wave is,(a) 165 Hz (b) 150 Hz(c) 660 Hz (d) 330 HzAnswer: (c)

17 Out of the given four waves (1), (2), (3) and (4)y 20 sin (100 t)…………(1)y 20 sin (101 t)…………(2)y 20 cos (100 t)…………(3)y 20.1 sin (100 t)…………(4)Emitted by four different sources S1, S2, S3 and S4 respectively, interference phenomena would be observed in space under appropriate conditions when(CPMT-88)(a) Source S1 emits wave (1) and S4 emits wave (4) (b) Source S2 emits wave (2) and S4 emits wave (4)(c) Source S1 emits wave (1) and S3 emits wave (3) (d) Interference phenomenon can not be observed by the

combination of any of the above waves.Answer: (c)

18 The equation of a progressive wave is

y 8 sin . The wavelength of the wave is (MHT CET 2002) (a) 8 m (b) 4 m(c) 2 m (d) 10 mAnswer: (a)

19 A source is moving towards observer with a speed of 20 m/s and having frequency 240 Hz and observer is moving towards source with a velocity 20 m/s. what is the apparent frequency heard by observer if velocity of sound 340 m/s?(a) 270 Hz (b) 240 Hz(c) 268 Hz (d) 360 HzAnswer: (a)

20 Sound wave is an example of (AFMC PUNE-2001)(a) Longitudinal wave(b) Transverse wave(c) Stationary wave(d) All of theseAnswer: (a)

21Two sound waves have wavelengths m and in air. Each wave produces 4 beats/seconds with a third note of fixed frequency. Find the frequency of the third note. (MHT-CET 2005)

(a) 684 Hz (b) 342 Hz(c) 680 Hz (d) 688 HzAnswer: (a)

22 The velocity o sound in a gas at 30C is approximately (CPMT-83)(a) 332 m/s (b) 350 m/s(c) 530 m/s (d) 332 km/sAnswer: (b)

23 Transverse waves can travel through(a) Air, water and a copper wire(b) Air and copper wire but not through water(c) A copper wire but not through air and water(d) Water but not through air and a copper wireAnswer: (c)

24 Velocity of sound is (CPMT-72)(a) Directly proportional to absolute temperature ( T) (b)

(c)

(d) Answer: (b)

25 Audible waves have a frequency (AFMC PUNE-95)(a) 0 10,000 Hz (b) 20 10,000 Hz(c) 20 20 kHz(d) 20 40 kHzAnswer: (c)


1. A astronaut can’t hear the explosion on the surface of the moon because (CPMT-78)(a) Frequency of explosion is out of audible range (b) Temperature at that point is very low(c) There is no medium on moon(d) None of aboveAnswer: (c)

2. Ultrasonic, infrasonic and Audible waves travel through a medium with speeds u, i, a respectively, then (CPMT-89)(a) u, i, a are nearly equal (b) u a i(c) u a i (d) a u and u iAnswer: (a)

3. A tuning fork when sounded together with a tuning fork of frequency 256 emits two beats. On loading the tuning fork of frequency 256 Hz. The number of beats heard are one per second. the frequency of tuning fork is (NCERT-75)(a) 257 Hz (b) 258 Hz

(c) 256 Hz (d) 254 HzAnswer: (d)

4. Sound travels 40 m during 20 vibrations its wavelength is, (AFMC-PUNE 96)(a) 0.5 m (b) 2 m(c) 3 m (d) 4 mAnswer: (b)

5. A sound wave ahs frequency 500 Hz and velocity 360m/sec. what is the distance between two particleshaving phase difference of 60 (NCERT-90, CPMT 90)(a) 0.7 cm (b) 12.0 cm(c) 70 cm (d) 120.0 cmAnswer: (b)

6. Two adjacent piano keys are struck simultaneously. The notes emitted by them have frequencies n1 and n2. the number of beats heard per second is (CPMT-74, 78)

(a)

(b) (c) (n1 n2) (d) 2 (n1 n2)Answer: (c)

7. Beats are produced when two sound waves given byy1 A sin 200 t and y2 A sing 210 t are sounded together. How many beats are produced/sec?(a) 3(b) 4(c) 5(d) 6Answer: (c)

8. Two waves of same amplitude and frequency arrive at point simultaneously. The resultant amplitude is same as amplitude of each wave. So that initial phase difference of the two waves is (MHT CET 2001)

(a)

(b)

(c)

(d) Answer: (c)

9. An astronaut can’t hear his companion at the surface of the moon because (CPMT-78)(a) Produced frequencies are above the radio frequencies (b) There is no medium for sound propagation(c) Temperature is too low during night and too high during day

moon

(d) None of aboveAnswer: (b)

10 Elastic waves in a solid are(a) Only transverse (b) Only longitudinal(c) Either transverse or longitudinal (d) Neither transverse nor longitudinalAnswer: (c)

11 Which of the following statement is wrong(NCERT-73)(a) Changes in air temperature have no effect on the speed of

sound (b) Changes in air temperature have effect on the speed of sound.(c) The speed of sound in water is lower then in air (d) Both ‘a’ and ‘c’Answer: (d)

12 Which one of he following represents progressive wave (CBSE-94)(a) y A sin kx(b) y A sit t(c) y A cos (at bx c)(d) none of theseAnswer: (d)

13 The velocity of sound in air is not affected by change in (CPMT 72)(a) Moisture content of air (b) Temperature of air(c) Atmospheric pressure (d) Composition of airAnswer: (c)

14 Doppler effect is applicable for (AFMC PUNE-98)(a) Sound wave(b) Light waves(c) None of above(d) Both ‘a’ and ‘b’Answer: (d)

15 When a plane wave travels in a medium in the X-direction, the displacement of the particle is given byy (x, t) 0.01 sin 2 (t 0.1x) where y and x are measured in metres and t in seconds what is the wavelength of the wave? (NCERT-84)(a) 0.1 m (b) 10.0 m(c) 1 m (d) 100.0 mAnswer: (b)

16 If amplitude of waves at distance r from a point source is A, then amplitude at a distance 2 r will be(a) 2A (b) A

(c)

(d) Answer: (c)

17 If two tuning forks A and B are sounded together, they produce 4 beats per second. A is then slightly loaded with wax, they produce two beats when sounded again. The frequency of A is 256 Hz. The frequency of B will be (CPMT-76)(a) 250 Hz (b) 252 Hz

(c) 260 Hz (d) 262 HzAnswer: (b)

18 There are three sources of sound of equal intensity with frequencies 400, and 401 and 402 vibrations/sec. the number of beats heard per second is (MNR-80)(a) 0(b) 1(c) 2(d) 3Answer: (b)

19 The intensities of sound are in the ratio 1 : 16 for two waves of same frequency and traveling in same medium. Their amplitudes are in the ratio(EAM CET 83)(a) 1 : 4 (b) 1 : 16(c) 4 : 1 (d) 1 : 2Answer: (a)

20 The waves produced in a vibrating tuning fork are(a) Longitudinal in both the stem and the prongs (b) Transverse in both stem and the prongs(c) Longitudinal in prongs and transverse in stem (d) Longitudinal in stem and transverse in prongsAnswer: (d)

21 In a wave motion, the velocity of the wave (V) and the maximum particle velocity (VP) are related as

(a)

(b)

(c)

(d) Answer: (b)

22 The equation of displacement of two waves are given as y1 10 sin

andy2 5 (sin 3 t then, what is the ratio of their amplitudes (AIIMS-97)(a) 1 : 2 (b) 2 : 1(c) 1 : 1 (d) NoneAnswer: (c)

23 A transverse wave described by the equation y y0

sin 2 . The maximum particle velocity is equal to four times the wave velocity. Then (IIT 84)

(a)

(b) (c) y0 (d) 2 y0Answer: (b)

24 A tunning fork C is sound with another fork D of frequency 384 Hz gives 4 beats/sec. When C is filed, the beat frequency become 3 beates/sec, then original frequency of tunning fork K is (MHT-CET 2006)(a) 388 Hz (b) 380 Hz(c) 387 Hz (d) 381 HzAnswer: (b)

25The phase difference between two points is . If the frequency of wave is 50 Hz. Then what is the distance between two points (Given 330 m/s)(MHT CET 2004)(a) 2.2 m (b) 1.1 m(c) 0.6 m (d) 1.7 mAnswer: (b)

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