## Class 11 Physics MCQs Waves for JEE/NEET

Here, you will get Class 11 Physics MCQ of Chapter 15 Waves for cracking JEE and NEET/AIIMS. By solving these MCQs of Class 11 Physics Chapter 15 Waves, you will get the confidence to crack JEE or NEET. Practice MCQ Questions for Class 11 Physics with Answers on a daily basis and score well in exams.

## Waves Class 11 MCQs Questions with Answers

The velocity of sound in any gas depends upon
(a) wavelength of sound only
(b) amplitude and frequency of sound
(c) density and elasticity of the gas
(d) intensity of sound waves only

Answer: (c) density and elasticity of the gas

When a tuning fork vibrates, the waves produced in tuning the Fork are
(a) transverse both in the prongs and the stem
(b) longitudinal in both the prongs and stem
(c) longitudinal in stem and transverse in prongs
(d) longitudinal in prongs and transverse in the stem

Answer: (c) longitudinal in stem and transverse in prongs

In an open organ pipe, which harmonics are missing?
(a) even
(b) odd
(c) depends upon the length of the pipe
(d) none of the above

Answer: (d) none of the above

Name the type of vibrations that are produced in a sitar wire
(a) progressive transverse
(b) progressive longitudinal
(c) stationary longitudinal
(d) stationary transverse

The extension in a string, obeying Hookes law is X. The speed of sound in the stretched string is V. If the extension in the string is increased to 1.5 X, the speed of sound will be
(a) 1.22 V
(b) 0.61 V
(c) 1.50 V
(d) 0.75 V

Reverberation is caused by
(a) refraction
(b) absorption
(c) reflection
(d) interference

A siren placed at a railway platfrom 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 velocity of train B to that of train A is
(a) 242 / 252
(b) 2
(c) 5 / 6
(d) 11 / 6

An organ pipe, open at both the ends, produces
(a) longitudinal progressives waves
(b) longitudinal stationary waves
(c) transverse stationary waves
(d) transverse progressive waves

A source of sound moves towards a stationary listener. The apparent pitch of the sound is found to be higher than its actual value. This happens because
(a) wavelength of the sound increases
(b) wavelength of the sound decreases
(c) the number of waves received by the listener decreases
(d) the number of waves received by the listener increases

Answer: (b) wavelength of the sound decreases

Pitch depends upon the
(a) amplitude
(b) wavelength
(c) frequency
(d) speed

Four wires of identical lengths, diameters and material and stretched on a sonometer box. The ratio of their tension is 1 : 4 : 9 : 16. the ratio of their fundamental frequencies is
(a) 1 : 6 : 9 : 16
(b) 4 : 3 : 2 : 1
(c) 1 : 2 : 3 : 4
(d) 1 : 4 : 9 : 16

Answer: (c) 1 : 2 : 3 : 4

A resonance air column of length 40 cm resonates with a tuning fork of frequency 450 Hz. Ignoring end correction, the velocity of sound in air will be
(a) 720 m/s
(b) 820 m/s
(c) 920 m/s
(d) 1020 m/s

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

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 velocity of train B to that of train A is
(a) 242 / 252
(b) 2
(c) 5 / 6
(d) 11 / 6

An observer is moving towards a stationary source of frequency 250 Hz with a velocity of 40 m/s. If the velocity of sound is 330 m/s, the apparent frequency heard by the observer will be
(a) 320 Hz
(b) 300 Hz
(c) 280 Hz
(d) 260 Hz

A train, standing in a station yard, blows a whistle of frequency 400 Hz in still air. The wind starts blowing in the direction from the yard to the station with a speed of 10 m/s. Given that the speed of sound in still air is 340 m/s
(a) the frequency of sound as heard by an observer standing on the platform is 400 Hz
(b) the speed of sound for the observer standing on the platform is 400 m/s
(c) the frequency of sound as heard by the observer standing on the platform will increase
(d) the frequency of sound as heard by the observer standing on the platform will decrease

Answer: (a) the frequency of sound as heard by an observer standing on the platform is 400 Hz

Transverse are generated in two uniform wires A and B by attaching their free ends to a vibrating source of frequency 600 Hz. The diameter of wire A is one-third that of wire B and tension in the wire A is double that in wire B. What is the ratio of velocities of waves of waves in wire A and B?
(a) √3 : 2
(b) 2 : √3
(c) 3 : √2
(d) √2 : 3

A transverse harmonic wave on a string is described by y (x,t) = 3.0 sin (36t + 0.018x + π/4) where x and y are in cm and t is in s. The positive direction of x is from left to right
(a) the wave is travelling from left to right
(b) the speed of the wave is 26 m/s
(c) frequency of the wave is 5.7 Hz
(d) the least distance between two successive crests in the wave is 2.5 cm

Answer: (c) frequency of the wave is 5.7 Hz

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

The equation of wave traveling along string is y = 3 cos p (100t – x) in C.G.S. unit then wavelength is
(a) 1 m
(b) 2 cm
(c) 5 cm
(d) None of above

When a compression is incident on rigid wall it is reflected as
(a) Compression with a phase change of p
(b) Compression with no phase change
(c) Rarefaction with a phase change of p
(d) Rarefaction with no phase change

Answer: (a) Compression with a phase change of p

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: (a) Speed of sound waves is more

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

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 wavelength

Answer: (a) Two sources which emit radiation of nearly the same frequency

Loudness of a note of sound is
(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 wave

Answer: (b) Directly proportional to square of amplitude of wave

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
(a) 409
(b) 429
(c) 517
(d) 500

String is in fundamental mode of vibration then velocity is directly proportional to _______
(a) Square root of tension
(b) Square root of length
(c) Square of tension
(d) Square root of linear density

Answer: (a) Square root of tension

A resonating column of air contains
(a) Stationary longitudinal waves
(b) Stationary transverse waves
(c) Transverse progressive waves
(d) Longitudinal progressive waves

For which of the following do the longitudinal waves exist?
(a) Both
(b) Air
(c) Water
(d) None of these

The extension in a string, obeying Hookes law is X. The speed of sound in the stretched string is V. If the extension in the string is increased to 1.5 X, the speed of sound will be
(a) 1.22 V
(b) 0.61 V
(c) 1.50 V
(d) 0.75 V

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

The wavelength of sound in air is 10 cm. its frequency is, (Given velocity of sound = 330 m/s)
(a) 330 cycles per second
(b) 3.3 kilo cycles per second
(c) 30 mega-cycles per second
(d) 305 cycles per second

Answer: (b) 3.3 kilo cycles per second

Energy is not carried by
(a) Longitudinal progressive waves
(b) Electromagnetic waves
(c) Transverse progressive waves
(d) Stationary wave

The velocity of sound is maximum in
(a) Water
(b) Air
(c) Vacuum
(d) Metal

The velocity of sound in a gas is proportional to :
(a) the isothermal elasticity
(c) square root of the isothermal elasticity
(d) square root of the adiabatic elasticity

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: (a) Neither pressure nor density

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

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

Which of the following expressions is that of a simple harmonic progressive wave
(a) a sin wt
(b) a sin (wt) cos (kx)
(c) a sin (wt – kx)
(d) a cos kx

Answer: (c) a sin (wt – kx)

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
(a) 2 sec
(b) 0.5 sec
(c) 250 sec
(d) 252 sec