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Practice QuestionsMCQ (Single Correct Answer)
1
┬а
A pipe open at both ends has a fundamental frequency $f$ in air. The pipe is now dipped vertically in a water drum to half of its length. The fundamental frequency of the air column is now equal to:
NEET 2025
2
The displacement of a travelling wave $$y=C \sin \frac{2 \pi}{\lambda}$$ (at $$-x$$) where $$t$$ is time, $$x$$ is distance and $$\lambda$$ is the wavelength, all in S.I. units. Then the frequency of the wave is
NEET 2024 (Re-Examination)
3
The $$4^{\text {th }}$$ overtone of a closed organ pipe is same as that of $$3^{\text {rd }}$$ overtone of an open pipe. The ratio of the length of the closed pipe to the length of the open pipe is :
NEET 2023 Manipur
4
The ratio of frequencies of fundamental harmonic produced by an open pipe to that of closed pipe having the same length is
NEET 2023
5
An organ pipe filled with a gas at 27$$^\circ$$C resonates at 400 Hz in its fundamental mode. If it is filled with the same gas at 90$$^\circ$$C, the resonance frequency at the same mode will be
NEET 2022 Phase 2
6
If the initial tension on a stretched string is doubled, then the ratio of the initial and final speeds of a transverse wave along the string is
NEET 2022 Phase 1
7
In a guitar, two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz. When tension in B is slightly decreased, the beat frequency of A is 530 Hz, the original freqnency of B will be :
NEET 2020 Phase 1
8
The fundamental frequency in an open organ
pipe is equal to the third harmonic of a closed
organ pipe. If the length of the closed organ
pipe is 20 cm, the length of the open organ
pipe is
NEET 2018
9
A tuning fork is used to produce resonance in
a glass tube. The length of the air column in
this tube can be adjusted by a variable piston.
At room temperature of 27┬░C two successive
resonances are produced at 20 cm and 73 cm
of column length. If the frequency of the tuning
fork is 320 Hz, the velocity of sound in air at
27┬░C is
NEET 2018
10
Two cars moving in opposite directions approach each other with speed of 22 m s$$-$$1 and 16.5 m s$$-$$1 respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is (velocity of sound is 340 m s$$-$$1)
NEET 2017
11
The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system ?
NEET 2017
12
Three sound waves of equal amplitudes have frequencies (n $$-$$ 1), n, (n + 1). They superimpose to give beats. The number of beats produced per second will be
NEET 2016 Phase 2
13
The second overtone of an open organ pipe has the same frquency as the first overtone of a closed pipe L metre long. The length of the open pipe will be
NEET 2016 Phase 2
14
A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15 m s$$-$$1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is
(Take velocity of sound in air = 330 m s$$-$$1)
(Take velocity of sound in air = 330 m s$$-$$1)
NEET 2016 Phase 1
15
A uniform rope of length L and mass m1 hangs vertically from a rigid support. A block of mass m2 is attached to the free end of the rope. A transverse pulse of wavelength $$\lambda $$1 is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is $$\lambda $$2. The ratio $$\lambda $$2/$$\lambda $$1 is
NEET 2016 Phase 1
16
An air column, closed at one end open at the other, resonates with a tuning fork when the smallest length of the column is 50 cm. The next larger length of the column resonating with the same tuning fork is
NEET 2016 Phase 1
17
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 the ends is
AIPMT 2015
18
A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 m s$$-$$1 at an angle of 60o with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 m s$$-$$1), is
AIPMT 2015
19
4.0 g of a gas occupies 22.4 litres at NTP. The specific heat capacity of the gas at constant volume is 5.0 J K$$-$$1 mol$$-$$1. If the speed of sound in this gas at NTP is 952 m s$$-$$1, then the heat capacity at constant pressure is
(Take gas constant R $$=$$ 8.3 J K$$-$$1 mol$$-$$1)
(Take gas constant R $$=$$ 8.3 J K$$-$$1 mol$$-$$1)
AIPMT 2015
20
A string is stretched between fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is
AIPMT 2015
21
The number of possible natural oscillations of air column in a pipe closed at one end length 85 cm whose frequencies lie below 1250 Hz are (Velocity of sound = 340 m s$$-$$1)
AIPMT 2014
22
A speeding motorcyclist sees traffic jam ahead him. He slows down to 36 km hour$$-$$1. He finds that traffic has eased and a car moving ahead of him at 18 km hour$$-$$1 is honking at a frequency of 1392 Hz. If the speed of sound is 343 m s$$-$$1, the frequency of the honk as heard by him will be
AIPMT 2014
23
If n1, n2 and n3 are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by
AIPMT 2014
24
The length of the wire between two ends of a sonometer is 100 cm. What should be the positions of two bridges below the wire so that the three segments of the wire have their fundamental frequencies in the ratio 1 : 3 : 5.
NEET 2013 (Karnataka)
25
Two sources P and Q produce notes of frequency 660 Hz. each. A listener moves from P to Q with a speed of 1 ms$$-$$1. If the speed of sound is 330 m/s, then the number of beats heard by the listener per second will be
NEET 2013 (Karnataka)
26
A source of unknown frequency gives 4 beats/s when sounded with a source of known frquency 250 Hz. The second harmonic of the source of unknown frequency gives five beats per second, when sounded with a source of frequency 513 Hz. The unknown frequency is
NEET 2013
27
If we study the vibration of a pipe open at both ends. then the following statement is not true.
NEET 2013
28
A wave travelling in the + ve x-direction having displacement along y-direction as 1 m, wavelength 2$$\pi $$ m and frequency of $${1 \over \pi }$$ Hz is represented by
NEET 2013
29
A train moving at a speed of 220 m s$$-$$1 towards a stationary object, emits a sound of frequency 1000 Hz. Some of the sound reaching the object gets reflected back to the train as echo. The frequency of the echo as detected by the driver of the train is
(Speed of sound in air is 330 m s$$-$$1)
(Speed of sound in air is 330 m s$$-$$1)
AIPMT 2012 Mains
30
The equation of a simple harmonic wave is given by
y = 3 sin$${\pi \over 2}$$(50t $$-$$ x),
where x and y are in metres and t is in seconds. The ratio of maximum particle velocity to the wave velocity is
y = 3 sin$${\pi \over 2}$$(50t $$-$$ x),
where x and y are in metres and t is in seconds. The ratio of maximum particle velocity to the wave velocity is
AIPMT 2012 Mains
31
Two sources of sound placed close to each other, are emitting progressive waves given by
y1 = 4sin600$$\pi $$t and y2 = 5sin608$$\pi $$t
An observer located near these two sources of sound will hear
y1 = 4sin600$$\pi $$t and y2 = 5sin608$$\pi $$t
An observer located near these two sources of sound will hear
AIPMT 2012 Prelims
32
When a string is divided into three segments of length $$l$$1, $$l$$2 and $$l$$3 the fundamental frequencies of these three segments are $${\upsilon _1},{\upsilon _2}$$ and $${\upsilon _3}$$ respectively. The original fundamental frequency ($$v$$) of the string is
AIPMT 2012 Prelims
33
Two identical piano wires, kept under the same tension T have a fundamental frequency of 600 Hz. The fractional increase in the tension of one of the wires which will lead to occurrence of 6 beats/s when both the wires oscillate together would be
AIPMT 2011 Mains
34
Sound waves travel at 350 m/s through a warm air and at 3500 m/s through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from warm air
AIPMT 2011 Prelims
35
Two waves are represented by the equations
y1 = $$a$$sin($$\omega $$t + kx + 0.57) m and
y2 = acos($$\omega $$t + kx) m, where x is in meter and t $$in$$ sec. The phase difference between them is
y1 = $$a$$sin($$\omega $$t + kx + 0.57) m and
y2 = acos($$\omega $$t + kx) m, where x is in meter and t $$in$$ sec. The phase difference between them is
AIPMT 2011 Prelims
36
A tuning fork of frequency 512 Hz makes 4 beats per second with the vibrating string of a piano. The beat frequency decreases to 2 beats per sec when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was
AIPMT 2010 Prelims
37
A transverse wave is represented by
y = Asin($$\omega $$t $$-$$ kx). For what value of the wavelength is the wave velocity equal to the maximum particle velocity ?
y = Asin($$\omega $$t $$-$$ kx). For what value of the wavelength is the wave velocity equal to the maximum particle velocity ?
AIPMT 2010 Prelims
38
The driver of a car travelling with speed 30 m/s towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 m/s, the frequency of reflected sound as heard by driver is
AIPMT 2009
39
A wave in a string has an amplitude of 2 cm. The wave travels in the +ve direction of x axis with a speed of 128 m/s. and it is noted that 5 complete waves fit in 4m length of the string. The equation describing the wave is
AIPMT 2009
40
Each of the two strings of length 51.6 cm and 49.1 cm are tensioned separately by 20 N force. Mass per unit length of both the strings is same and equal to 1 g/m. When both the strings vibrate simultaneously the number of beats is
AIPMT 2009
41
The wave described by y = 0.25 sin(10$$\pi $$x $$-$$ 2$$\pi $$t), where x and y are in metres and t in seconds, is a wave travelling along the
AIPMT 2008
42
Two periodic waves of intensities $$I$$1 and $$I$$2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is
AIPMT 2008
43
A point performs simple harmonic oscillation of period T and the equation of motion is given by x = a sin($$\omega $$t + $$\pi $$/6). After the elapse of what fraction of the time period the velocity of the point will be equal to half of its maximum velocity?
AIPMT 2008
44
A transverse wave propagating along x-axis is represented by y(x, t) = 8.0 sin (0.5 $$\pi $$x $$-$$ 4$$\pi $$t $$-$$ $$\pi $$/4) where x is in metres and t is in seconds. The speed of the wave is
AIPMT 2006
45
Two vibrating tuning forks produce waves given by y1 = 4 sin 500$$\pi $$t and y2 = 2 sin506 $$\pi $$t. Number of beats produced per minute is
AIPMT 2006
46
Two sound waves with wavelengths 5.0 m and 5.5. m respectively, each propagate in a gas with velocity 330 m/s. We expect the following number of beats per second.
AIPMT 2006
47
The time of reverberation of a room A is one second. What will be the time (in seconds of reverberation of a room, having all the dimensions double of those of room A ?
AIPMT 2006
48
Which one of the following statements is true ?
AIPMT 2006
49
A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distances of 2 m and 3 m respectively from the source. The ratio of the intensities of the waves at P and Q is
AIPMT 2005
50
The phase difference between two waves. represented by
y1 = 10$$-$$6 sin[100t + (x/50) + 0.5] m
y2 = 10$$-$$6 cos[100t + (x/50)] m,
where x is expressed in metres and t is exressed in secondss, is approximately.
y1 = 10$$-$$6 sin[100t + (x/50) + 0.5] m
y2 = 10$$-$$6 cos[100t + (x/50)] m,
where x is expressed in metres and t is exressed in secondss, is approximately.
AIPMT 2004
51
A car is moving towards a high cliff. The driver sounds a horn of frequency $$f$$. The reflected sound heard by the driver has frequency $$2f$$. If v is the velocity of sound, then the velocity of the car, in the same velocity units, will be
AIPMT 2004
52
An observer moves towards a stationary source of sound with a speed 1/5th of the speed of sound. The wavelength and frequency of the source emitted are $$\lambda $$ and $$f$$ respectively. The apparent frequency and wavelength recorded by the observer are respectively
AIPMT 2003
53
A wave travelling in positive X-direction with a $$=$$ 0.2 ms$$-$$2, velocity = 360 ms$$-$$1 and $$\lambda $$ $$=$$ 60 m, then correct expression for the wave is
AIPMT 2002
54
A whistle revolves in a circle with angular speed $$\omega $$ = 20 rad/s using a string of length 50 cm. If the frequency of sound from the whistle is 385 Hz, then what is the minimum frequency heard by an observer which is far away from the centre (velocity of sound $$=$$ 340 m/s)
AIPMT 2002
55
The equation of a wave is represented by
y $$=$$ 10$$-$$4 sin(100t $$-$$ $${x \over {10}}$$) m. then the velocity of wave will be
y $$=$$ 10$$-$$4 sin(100t $$-$$ $${x \over {10}}$$) m. then the velocity of wave will be
AIPMT 2001
56
If the tension and diameter of a sonometer wire of fundamental frequency n is doubled and density is halved then its fundamental frequency will become
AIPMT 2001
57
Two waves having equation x1 = $$a$$sin($$\omega $$t $$-$$ kx + $$\phi $$1), x2 = asin($$\omega $$t $$-$$kx + $$\phi $$2). If in the resultant wave the frequency and amplitude remain equal to amplitude of superimposing waves, the phase difference between them is
AIPMT 2001
58
A string is cut into three parts, having fundamental frequencies n1, n2, n3 respectively. Then original fundamental frequency n related by the expression as
AIPMT 2000
59
Two stationary sources each emitting waves of wavelength $$\lambda $$, an observer moves from one source to another with velovcity u. Then number of beats heard by him
AIPMT 2000
60
The equations of two waves acting in perpendicular directions are given as
x = $$a$$cos($$\omega $$t +$$\delta $$) and y = $$a$$cos($$\omega $$t + $$\alpha $$), where $$\delta $$ = $$\alpha $$ + $${\pi \over 2}$$, the resultant wave represents
x = $$a$$cos($$\omega $$t +$$\delta $$) and y = $$a$$cos($$\omega $$t + $$\alpha $$), where $$\delta $$ = $$\alpha $$ + $${\pi \over 2}$$, the resultant wave represents
AIPMT 2000