CBSE Class 11 Physics Waves MCQs

Question: When a sound wave goes from one medium to another, the quantity that remains unchanged is

a) frequency

b) wavelength

c) amplitude

d) speed

Answer: frequency

Question: For which of the following do the longitudinal waves exist?

a) Both

b) Air

c) Water

d) None of these

Answer: Both

Question: Sound travels in rocks in the form of

a) both longitudinal and transverse elastic waves

b) non-elastic waves

c) transverse elastic waves only

d) longitudinal elastic waves only

Answer: both longitudinal and transverse elastic waves

Question: From a point source, if amplitude of waves at a distance r is A, its amplitude at a distance 2r will be

a) A/2

b) A/4

c) 2 A

d) A

Answer: A/2

Question: The property of a medium necessary for wave propagation is

a) All of the above

b) Elasticity

c) Inertia

d) Low resistance

Answer: All of the above

Question: The ratio of the speed of a body to the speed of sound is called

a) Mach number

b) Sonic index

c) Doppler ratio

d) Refractive index

Answer: Mach number

Question: Sound waves transfer

a) both energy and momentum

b) only energy not momentum

c) momentum

d) energy

Answer: both energy and momentum

Question: The reason for introducing Laplace correction in the expression for the velocity of sound in a gaseous medium is

a) no change in the heat of the medium during the propagation of the sound through it

b) no change in the temperature of the medium during the propagation of the sound through it

c) change in the pressure of the gas due to the compression and rarefaction

d) change in the volume of the gas

Answer: no change in the heat of the medium during the propagation of the sound through it

Question: Which of the following changes at an antinode in a stationary wave?

a) Neither pressure nor density

b) Both pressure and density

c) Pressure only

d) Density only

Answer: Neither pressure nor density

Question: What is the effect of humidity on sound waves when humidity increases?

a) Speed of sound waves is more

b) Speed of sound waves is less

c) Speed of sound waves remains same

d) Speed of sound waves becomes zero

Answer: Speed of sound waves is more 

Question: Which of the following statements is/are correct about the standing wave?

I. In a standing wave the disturbance produce is confined to the region where it is produced.

II. In a standing wave, all the particles cross their mean position together.

III. In a standing wave, energy is transmitted from one region of space to other

a) I and II

b) Only II

c) Only III

d) I, II and III

Answer: I and II

Question: The rate of transfer of energy in a wave depends

a) directly on the square of the wave amplitude and square of the wave frequency

b) directly on the square of the wave amplitude and root of the wave frequency

c) directly on the wave amplitude and square of the wave frequency

d) None of these

Answer: directly on the square of the wave amplitude and square of the wave frequency

Question: If vibrations of a string are to be increased by a factor of two, then tension in the string must be made

a) twice

b) eight times

c) half

d) four times

Answer: twice

Question: The fundamental frequency of a closed end organ pipe is n. Its length is doubled and radius is halved. Its frequency will become nearly

a) n/2

b) n/3

c) n

d) 2 n

Answer: n/2

Question: The fundamental frequency of an organ pipe is 512 Hz. If its length is increased, then frequency will

a) decrease

b) increase

c) remains same

d) cannot be predicted

Answer: decrease

Question: What is the effect of increase in temperature on the frequency of sound produced by an organ pipe?

a) increases

b) no effect

c) decreases

d) erratic change

Answer: increases

Question: Frequencies of sound produced from an organ pipe open at both ends are

a) even and odd harmonics

b) only odd harmonics

c) only even harmonics

d) only fundamental note

Answer: even and odd harmonics

Question: closed organ pipe (closed at one end) is excited to support the third overtone. It is found that air in the pipe has

a) four nodes and four antinodes

b) four nodes and three antinodes

c) three nodes and four antinodes

d) three nodes and three antinodes

Answer: four nodes and four antinodes

Question: If there are six loops for 1 m length in transverse mode of Melde’s experiment., the no. of loops in longitudinal mode under otherwise identical conditions would be

a) 3

b) 6

c) 12

d) 8

Answer: 3

Question: 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 theends is

a) 120 cm

b) 140 cm

c) 80 cm

d) 100 cm

Answer: 120 cm