11th class (Fsc) Physics unit 8 MCQs
51. According to Laplace’s correction, the formula for the speed of sound in air is:
a. √P/q
b. √ɤp/q
c. √rP/q
d. √E/q
52. The velocity of sound in air at 0oC is:
a. 222 ms-1
b. 332 ms-1
c. zero
d. 332 cms-1
53. Speed of sound in air is independent of:
a. Humidity
b. Density
c. Temperature
d. Pressure
54. Sound travel faster in:
a. O2
b. CO2
c. He
d. H2
55. The speed of sound in air would become double than its speed at 10oC at a temperature of:
a. 859sC
b. 313sC
c. 899sC
d. 586sC
56. Newton’s formula for velocity of sound in gas / air is related as under:
a. ʋ = √Sδ
b. V= E/δ
c. ʋ = Sδ
d. ʋ= E/δ
57. The speed of sound is greater in solids than in gases due to their height:
a. Ammonia
b. Air
c. Water
d. Steel
58. The speed of sound is greater in solids due to their high:
a. Temperature
b. Density
c. Eleasticity
d. Pressure
59. Increase in the velocity of sound in air for 1oC rise in temperature is:
a. 161 ms-1
b. 61 ms-1
c. 261 ms-1
d. 0.61 ms-1
60. Increase in speed of sound for 1oC rise in temperature is:
a. 61 ms-1
b. 0.61 ms-1
c. 6.1 ms-1
d. 0.61 cms-1
61. If the pressure of a gas is doubled, then speed of sound is:
a. Not affected
b. Doubled
c. Increases by four times
d. Become half
62. Velocity of sound in air is independent of:
a. Density
b. Temperature
c. Medium
d. Pressure
63. With increase of temperature, the speed of sound:
a. Decreases
b. Remains constant
c. Increases
d. Becomes zero
64. In which medium the speed of sound is greater?
a. water
b. Oxygen
c. Copper
d. Air
65. According to Laplace’s correction, the formula for the speed of sound in air:
a. √p/q
b. √rp/q
c. √rp/q
d. √e/q
66. Speed of sound in vacuum is:
a. 333 ms-1
b. 280 ms-1
c. 0 ms-1
d. 332 ms-1
67. The value of ” γ” for mano-atomic gas is:
a. 1.29
b. 1.67
c. 1.45
d. 1.40
68. Speed of sound in aluminum at 20oC is:
a. 5130 m /s
b. 3600 m /s
c. 5500 m /s
d. 5100 m /s
69. Frequency range of hearing of cats is:
a. 60-20000 Hz
b. 20-20000 Hz
c. 60-70000 Hz
d. 10-10000 Hz
70. Speed of sound in copper is:
a. 3500 ms-1
b. 3800 ms-1
c. 3400 ms-1
d. 3600 ms-1
71. The velocity of sound is maximum at 20oC in:
a. Glass
b. Lead
c. iron
d. Copper
72. The value of constant ‘y’ for diatomic gas is
a. 1.45
b. 1.67
c. 1.40
d. 1.29
73. The speed of sound is greatest in:
a. Ammonia
b. Air
c. Water
d. Steel
74. Beats cannot be recognized if difference of frequencies of two sound is:
a. Less than 5 Hz
b. Less than 10 Hz
c. Less than 7 Hz
d. More than 10 Hz
75. Beats can be heard when difference of frequency is not more than:
a. 4 Hz
b. 8 Hz
c. 6 Hz
d. 10 Hz
76. In order to produce beats, the two sound waves should have:
a. The same frequency
b. The same amplitude
c. Slightly different frequencies
d. Slightly different amplitude
77. The basic principle of beats is:
a. Reflection
b. Interference
c. Refraction
d. Refraction
78. Beats cannot be heard if the difference of frequency is more than:
a. 5 Hz
b. 7 Hz
c. 20 Hz
d. 10 Hz
79. When two notes of frequencies f1 and f2 are sounded together, beats are formed. If f1>f2 what will be the beat frequency?
a. f1 – f2
b. f1 + f2
c. 1/2(f1 – f2)
d. 1/2(f1 + f2)
80. The periodic variations of sound between maximum and minimum loudness are called:
a. Laplace correction
b. Doppler’s effect
c. Beats
d. Reflection
81. Beats are produced due to:
a. Bernoulli’s effect
b. Super position of sound waves
c. Diffraction of sound
d. Polarization of waves
82. Beats detectable easily upto frequency difference between two sound is:
a. 10 Hz
b. 2 Hz
c. 32 Hz
d. 6 Hz
83. On reflection from denser medium light wave undergoes a phase change of:
a. 3𝜋/2 rad
b. 𝜋 rad
c. 2𝜋 rad
d. 𝜋/2 rad
84. When wave is reflected from the boundary of denser medium then phase of wave changes by:
a. 180o
b. 0o
c. 27o
d. 90o
85. When a transverse wave is incident on rare medium from a denser medium, the phase change will be:
a. 180o
b. 90o
c. 0o
d. 60o
86. In vibrating string, the points where the amplitude is maximum are called:
a. Troughs
b. Nodes
c. Crests
d. Antinodes
87. In stationary waves, the velocity of particle at the node is:
a. zero
b. Maximum
c. Variable
d. Infinite
88. In stationary waves the points which always remain at rest are:
a. Crest
b. Nodes
c. Trough
d. Antinodes
89. The distance between two consecutive antinode is:
a. λ
b. λ/4
c. 2λ
d. λ/2
90. The distance between consecutive node and anti-node:
a. 2λ
b. λ
c. λ/4
d. λ/2
91. The distance between two consecutive nodes is:
a. 2λ
b. λ/2
c. λ
d. λ/4
92. The number of nodes between two consecutive antinodes is/are:
a. Three
b. one
c. Four
d. Two
93. The stationary waves consists of:
a. Nodes and anti-nodes
b. Crest and troughs
c. Reflection and rarefaction
d. Compressions and elongation
94. When two identical waves move in the opposite direction, the given rise to:
a. Constructive interference
b. Stationary waves
c. Destructive interference
d. Beats
95. The path difference for constructive interference should be:
a. mλ/2
b. λ/2
c. 3λ/2
d. 5λ/2
96. A set of frequencies which are multiples of the fundamental frequency are called:
a. Beat frequencies
b. Doppler effect
c. Harmonics
d. Nodal frequencies
97. If a string is fixed at both ends vibrates in ‘n’ loops, then wavelength in term of length ‘I’ of strings is given by:
a. 2L/n
b. nL/2
c. 2l/v
d. l/2n
98. The distance between 1st node and 4thantinode is:
a. 13/4 λ
b. 7/4 λ
c. 11/4 λ
d. 5/4 λ
99. When one end of organ pipe is closed, then the frequency of stationary waves of anyharmonic in it is given by:
a. fn = 4v/nL
b. fn = nv/2L
c. fn = nv/4L
d. fn = nL/4v
100. If the organ pipe is closed at one end, the frequency of fundamental harmonic is:
a. f1 = 4I/ʋ
b. f1 = ʋ/2I
c. f1 = 2I/ʋ
d. f1 = v/4I
101. Stars moving away from earth show a:
a. Doppler’s shift
b. Blue shift
c. Frequency shift
d. Red shift
102. When an observer is moving away from the source with velocity U
from a stationary source then relative velocity of the waves and the observer is:
a. v + uo / 2
b. ʋ + uo
c. Zero
d. v – uo
103. In sonar we use:
a. Radio waves
b. Sound waves
c. Microwaves
d. Ultrasound waves
104. Stars moving towards the earth show:
a. Yellow shirt
b. Red shirt
c. Green shirt
d. Blue shirt
105. Radar system is an application of:
a. Magnetic effect
b. Chemical effect
c. Doppler’s effect
d. Electrical effect
106. The speed of stars and galaxies can be calculated by:
a. Doppler’s effect
b. Compton effect
c. Pascal’s law
d. Stefan’s law
107. The waves used in radar speed trap are:
a. Microwaves
b. Longitudinal
c. Matter waves
d. Sound waves
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