Chapter # 8 Wave motion and Sound

PHYSICS

CHAPTER # 08 Wave Motion and Sound

1. 2.

3.

4. 5. 6.

7.

8.

9.

According to Hooke’s law the change in the length of a spring is directly proportional to: a) Its weight b) Applied force c) Its temperature d) Current passing through it Mathematically, Hooke’s law is stated as: 1 a) F = ma b) F = 2 kx2 1 c) F = 2 kx d) F = kx In simple Harmonic Motion the acceleration of a body is always directed towards and proportional to its displacement from: a) Its mean position b) The point at which it is attached to the wall c) The point at which force is applied d) None of these One complete round trip of a body about a mean position is called a: a) Rotation b) Vibration c) Period d) Frequency The maximum displacement of a vibrating body from the equilibrium position is called: a) Circumference b) Radius c) Amplitude d) Oscillation A point P is moving with uniform angular speed along a circle of radius r. The speed of its projection Q on the diameter will be: 2 2 2 a) V =  r  x b) V =  (r - x) 1  2 2 r  x  r2  x2 c) V = r d) V = The relation between the time period T and angular velocity  is given by: 1  a) T =  b) T = 2

k t kmt c) x = xo Cos d) x = xo Cos ( m ) The instantaneous velocity of a mass attached to a spring is given by:

a) V = xo

10.

11.

1

x xo

b) V = xo

m k

1

A

B C A

B

C xo

2

x2

2 2 k 1 x k 1 x 1 xo2 xo2 m c) V = xo m d) V = xo The kinetic energy of a mass attached to a spring is given by: 1 1 2 2 ( x  x ) o a) K.E. = 2 k b) K.E. = 2 k (xo2 – x2) 1 1 2 2 2 c) K.E. = 2 k (xo – x ) d) K.E. = 2 k (x2 – xo2) The kinetic energy of a mass attached to a spring is maximum at: a) Mean position b) Extreme position c) Between extreme position and mean position d) None of these

-1-

D

D

2  c) T = 2 d) T =  The displacement of a vibrating mass attached to a spring at time t is given by: k k t t m m a) x = xo Sin b) x = xo Cos

k m

B

B

A

PHYSICS

CHAPTER # 08 Wave Motion and Sound

12.

13.

The acceleration of a simple pendulum is given by: g a) a = ( - l ) x

l g

14.

15. 16.

17.

18. 19.

20. 21. 22.

23. 24.

A

g b) a = - ( l ) x 1 g c) a = - glx d) a = - 2 ( l ) x2 The angular velocity of a simple pendulum is given by: g lg a)  = l b)  =

A

g d)  = l

c)  = The frequency of a second’s pendulum is: a) 1 Hz

D

b) 2 Hz 1 c) 4 Hz d) 2 Hz The waves that require a medium for their propagation are called: a) Transverse waves b) Electromagnetic waves c) Matter waves d) Mechanical waves The speed of propagation of a wave is given by: T a) V =  T b) V =  2  c) V = T d) V = T Longitudinal waves are those in which the particles of the medium move: a) In the direction of wave motion b) Opposite to the direction of wave motion c) Back and forth parallel to the direction of the wave motion d) Perpendicular to the direction of waves A ripple tank is used to study: a) Nature of water b) Properties of light c) Various features of waves d) None of these Wavelength and time period are related to the velocity by the relation: V a)  = VT b)  = T T V  c) V = d) T =  Water waves are not perfectly transverse and their particles move in: a) Elliptical orbits b) Circular orbits c) Straight lines d) Slanting lines The bouncing back of a wave from the boundary of two different media is known as: a) Refraction b) Transmission c) Diffraction d) Reflection The energy transported through a unit area held perpendicular to the wave in one second is: 1 1 2 2 C2 r 2 C  r a) 2 b) 2 1 1 2 2 2 Cr 2  C r 2 c) d) 2 The points on the cord which do not oscillate in stationary wave are known as: a) Crests b) Troughs c) Nodes d) Antinodes The distance between two consecutive nodes or antinodes is the same and equal to: a) Half the wavelength b) Full wavelength c) Double the wavelength d) Three times the wavelength

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D D

C

C A

B D A

C A

PHYSICS

CHAPTER # 08 Wave Motion and Sound

25. 26.

When two exactly similar waves moving along the same line superimpose _______ are formed: C a) Transverse waves b) Longitudinal waves c) Stationary waves d) Mechanical waves If a stretched string of length l and mass m having tension T is plucked at its middle point, the B frequency of the stationary waves produced in it is given by:

2 a) f1 = l 1 c) f1 = 2l 27.

28.

29. 30.

31.

32.

33. 34. 35. 37.

T l m T m l

1 b) f1 = 2l

T l m

1 d) f1 = 2l

T l m2

If a stretched string vibrates in n loops then its frequency fn is given by: A a) fn = nf1 b) fn = n2f1 1 nf1 c) fn = n f1 d) fn = 2 A string of length l vibrates in n loops. The wavelength of the stationary waves produced is given by: D 2l l 2  n n 2 n a) = b) 2n 2l l c) d) n The sonometer is used to find out: A a) Frequency b) Amplitude c) Velocity d) None of these The frequency of the tuning fork determined with the help of a sonometer is given by: D 1 m 1 m a) f = 2l T b) f = l T T 1 2 T c) f = l m d) f = 2l m Longitudinal waves are also called: A a) Compressional waves b) Mechanical waves c) Transverse waves d) Radio waves  If E is the elasticity of a medium and is its density then according to Newton the velocity of sound B in that medium is given by the formula: E E  a) V =  b) V =  E c) V = E d) V = In compressional waves, the layer of medium having reduced pressure is called: D a) Compression b) Elasticity c) Node d) Rarefaction Sound cannot propagate through: D a) Walls b) Grass c) Wood d) Vacuum Velocity of sound increases with the _______ of the medium: C a) Surface area b) Viscosity c) Elasticity d) Depth Velocity of sound obtained from Newton’s formula comes out to be: A a) 280 ms-1 b) 180 ms-1 c) 330 ms-1 d) 110 ms-1

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PHYSICS

CHAPTER # 08 Wave Motion and Sound

38.

After Laplace’s correction, Newton’s formula for the velocity changes to:

 a) V =

P 

P 

b) V =

 P

  d) V = P

c) V = r The velocity of sound obtained by Laplace’s formula comes out to be approximately: a) 333 ms-1 b) 222 ms-1 -1 c) 1100 ms d) 110 ms-1 40. The exact value of the speed of sound is: a) 339 ms-1 b) 333 ms-1 -1 c) 33 ms d) None of these 41. The speed of sound in the air increases approximately by _______ for each degree rise in temperature: a) 1.6 ms-1 b) 2.6 ms-1 -1 c) 0.6 ms d) 6.1 ms-1 42. If V1 and V2 are velocities of sound at absolute temperatures T1 and T2 repectively then they can be related by the expression: V1 T1 T1 V2 V2 T V1 2 a) = T2 b) = V2 T2 V1 T1 V1 T c) = 1 d) V2 = T2 39.

44. 45.

46. 47. 48.

49. 50.

B

Intensity of sound is the _______ transmitted normally per second through a unit area: a) Number of waves b) Number of crests c) Number of troughs d) Amount of energy Mathematically, the intensity of sound is given by: E A E A  t a) I = b) I =  t t c) I = EA d) I = EA  t The SI units of intensity of sound are: a) Watt/m3 b) Joules/s2 -2 c) Erg m s d) Watt/m2 Loudness of sound depends on intensity as well as the _______: a) Frequency b) Amplitude c) Wavelength d) Ear According to the Weber-Fechner Law, loudness of sound is directly proportional to the _______ of intensity: a) Square b) Square root c) Cube root d) Logarithm The difference in _______ of two sounds is known as intensity level: a) Loudness b) Frequency c) Wavelength d) Energy The intensity level of sound of intensity I w.r.t. the intensity of faintest audible sound I o is obtained by the formula: Io a) I.L. = K log ( I ) b) I.L. = KIo log I I I c) I.L. = IK log I d) I.L. = K log ( o )

A B C D

D A

D D D

A D

o

51. 52.

The unit of intensity level of sound is called a: a) Joule c) Lumen The intensity of ordinary conversation is: a) 10-3 watt/m2 c) 10-9 watt/m2

B b) Bel d) Hertz B b) 10-6 watt/m2 d) 10-12 watt/m2

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PHYSICS

CHAPTER # 08 Wave Motion and Sound

53.

The intensity level of ordinary conversation is: a) 30 db b) 40 db c) 50 db d) 60 db 54. The intensity level of fainted audible sound is: a) 0.1 db b) 10-3 db -6 c) 10 db d) 0 db 56. The minimum frequency that a human can detect is: a) 2 Hz b) 20 Hz c) 200 Hz d) 2,000 Hz 57. The maximum frequency a human ear can detect is: a) 2,000 Hz b) 10,000 Hz c) 20,000 Hz d) 2  106 Hz 58. The human ear is most sensitive in the frequency range of: a) 2,000 to 4,000 Hz b) 4,000 to 8,000 Hz c) 3,000 to 6,000 Hz d) 5,000 to 11,000 Hz 59. Pitch is a sensation produced by sound that depends upon its _______: a) Velocity b) Intensity c) Amplitude d) Frequency 60. The characteristic of sound by which a sound of exactly the same pitch and loudness coming from another source is called the _______ of sound: a) Quality b) Quantity c) Sensitivity d) Intensity 61. When two waves superimpose on each other, their combined effect is called: a) Enhancement b) Interference c) Interaction d) None of these 62. When two bodies of slightly different frequencies are sounded simultaneously there are rises and falls in the loudness of the resultant sound called: a) Alterations b) Beads c) Beats d) None of these 63. Doppler’s effect is the change in the _______ of sound caused by the relative motion of the source and the listener: a) Velocity b) Frequency c) Amplitude d) Loudness 64. If V is the velocity of sound and ‘a’ is the velocity of the source approaching a listener then the frequency heard by the listener will be: Va aV V   a) f = f b) f = V f

65. 66. 67. 68. 69. 70.

aV V c) f  = V f d) f  = V  a f Applications of the results of scientific studies in the designs of buildings etc. is called: a) Optics b) Wave mechanics c) Acoustics d) Statics Echoes are produced by the _______ of sound: a) Reflection b) Interference c) Deflection d) Diffraction The echoing effect in which sound to be prolonged is called: a) Doppler effect b) Constructive interference c) Beats d) Reverberation Radio and Television programmes are produced by _______ for us: a) Sound waves b) Electromagnetic waves c) Translatory waves d) None of these _______ medium is essential to produce sound waves: a) Material b) Vibratory c) Elastic d) Light The waves which require medium for their motion are called _______ waves: a) Mechanical b) Vibratory c) Simple d) None of these

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D D B C A D A

B C

B

D

C A D B A A

PHYSICS

CHAPTER # 08 Wave Motion and Sound

71. 72. 73. 74. 75. 76. 77. 78. 79.

80. 81.

82.

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The waves which do not require any medium for their motion are called _______ waves: a) Mechanical b) Electromagnetic c) Positive d) Horizontal In pendulum, the to and fro motion is called _______ motion: a) Mechanical b) Elastic c) Vibratory d) None of these “Simple Harmonic Motion” is a type of _______ motion: a) Vibratory b) Elastic c) Mechanical d) Magnetic A motion which repeats itself in equal intervals of time is called _______: a) Displacement b) Periodic motion c) Negative d) Vertical motion The one complete round trip of a body is called _______: a) Vibration b) Circle c) Cable d) Equilibrium The time required to complete one vibration is called: a) Frequency b) Time period c) Amplitude d) None of these The total number of vibrations executed by a body in one second is called its _______: a) Time period b) Amplitude c) Wave d) Frequency The unit of frequency is _______: a) Hertz (Hz) b) Newton c) Cycles d) None of these The relation of frequency and time period is shown by the formula _______: 1 a) f = T b) f = T c) f = 2T d) None of these The maximum displacement of the body on either side of its equilibrium position is called _______: a) Displacement b) Vibration c) Time period d) Amplitude A force of 0.03N is required to displace a body attached to a spring through 0.2m from its equilibrium position, calculate the spring constant of the spring: a) K = 1.50 N/m b) K = 15.0 N/m c) K = 51.0 N/m d) K = 0.15 N/m A force of 15N is required to displace a body attached to a spring through 0.3 from its equilibrium position, calculate the spring constant of the spring: a) 50 N/m b) 5.0 N/m c) 0.5 N/m d) 0.05 N/m If the force applied on a spring is 50N and its displacement is 0.3m, find the value of spring constant: a) 4.7 N/m b) 76.76 N/m c) 166.67 N/m d) 67.77 N/m If the displacement of a spring is 0.5m and the spring constant value is 0.8N/m, then find the applied force: a) 0.4 N b) 0.6 N c) 0.8 N d) 0.12 N If the value of spring constant of any spring is 0.04 N/m and the value of displacement for spring is 3m, then find the required force: a) 0.12 N b) 12.0 N c) 1.2 N d) 2.1 N The formula for Hooke’s law is _______: a) F = ma b) F = Kx 2 mv 1 r c) Fc = d) Fc = 2 mv2

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B C A B A B D A A

D D

A

C

A

A

B

PHYSICS

CHAPTER # 08 Wave Motion and Sound

87.

88. 89. 90.

91. 92. 93. 94. 95. 96.

97.

99.

100. 101.

102. 103.

When a mass ‘m’ is attached to a spring then its acceleration will be _______: k m 3 a) a = m a b) a = k x k k c) a = - m x d) a = m x0 If the time period of a body which is attached with spring is 7.26 sec, then find its frequency: a) 9.13 vib s-1 b) 0.614 vib s-1 -1 c) 0.138 vib s d) 0.194 vib s-1 If the time period of a body which is attached with spring is 3.43 sec, then find its frequency: a) 3.29 vib s-1 b) 9.29 vib s-1 -1 c) 2.39 vib s d) 0.292 vib s-1 If the frequency of an object which is attached with a spring is 0.57 vibs -1, then find its angular speed (  ): a) 6.35 rad s-1 b) 5.36 rad s-1 c) 3.65 rad s-1 d) 3.58 rad s-1 If the frequency of a body which is attached to a spring is 0.636 vib s-1, then find its angular speed: a) 6 rad s-1 b) 5 rad s-1 -1 c) 8 rad s d) 4 rad s-1 The curve which gives the displacement as function of time is known as the wave form of _______: a) Simple Harmonic Motion b) Simple Motion c) Pendulum motion d) None of these The time period of second pendulum is _______: a) 4 sec b) 3 sec c) 2 sec d) 5 sec Those pendulums which have same lengths, have also same _______: a) Natural Period b) different frequency c) Different period d) None of these We can say that the frequency is the _______ of the time period T. a) Reciprocal b) Relation c) Directly d) Crests The general equation of wave-motion is _______: f  a) V = b) V = f   c) V = f d) V = f2  The wave in which any particle vibrates along the perpendicular line of wave propagation, are known as _______ waves: a) Crest b) Sound c) Transverse d) General When the wave advances through a surface of water, then water molecules move around circular paths at their _______ positions: a) Transverse b) Respective c) Inverse d) None of these A human ear can hear a sound of frequency _______: a) 80Hz ----- 100Hz b) 20Hz ----- 20,000Hz c) 200Hz ----- 500Hz d) None of these The characteristic of sound by which a shrill sound can be distinguished from a grave one is called a _______ sound: a) Musical sound b) Sound waves c) Pitch of sound d) None of these If a stretched string vibrates in a loop then its frequency ‘fn’ is given by: a) fn = nf1 b) fn = nf2 c) fn = nf3 d) None of these Velocity of sound _______ with the elasticity of the medium: a) Decreases b) Increases c) Zero d) None of these

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C

C D D

D A C A A B

C

B

B C

A B

PHYSICS

CHAPTER # 08 Wave Motion and Sound

104. 105.

The value of the speed of sound is _______: a) 301 m/s b) c) 504 m/s d) The unit of intensity level of sound is called _______: a) Bel b) c) watt d)

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D 741 m/s None of these A Joule None of these