CBSE Questions for Class 11 Engineering Physics Waves Quiz 9 - MCQExams.com

The refracted and the incident pulses for a wave travelling in a string have an amplitude ratio of 1:The ratio of their phases will be 
  • 1:2
  • 2:1
  • 1:1
  • 1:4
Principle of superposition can be applied to
  • EM waves
  • sound waves
  • Radio waves
  • All of the above
A progressive wave $$y = 10 sin (2t-4x)$$ gets reflected along a rigid boundary as $$y= 8 sin (2t+4x+\pi)$$ under certain conditions
  • True
  • False
Two waves of same amplitude and frequency and travelling in same direction are superimposed each other to give rise to a resultant wave of amplitude 2A
  • True
  • False
If the phase difference between two component waves of different amplitudes is $$2\pi$$, their resultant amplitude will become
  • sum of the amplitudes
  • difference of the amplitudes
  • product of the amplitudes
  • ratio of their amplitudes
The initial phase of a pulse travelling on a string is $$\pi/3$$. The reflected pulse has a phase of 
  • $$4 \pi/3$$
  • $$2 \pi/3$$
  • $$ \pi/3$$
  • $$5 \pi/3$$
The phase of the transmitted wave changes with frequency
  • True
  • False
The equation of an incident wave travelling along +X direction is given by $$y= A sin (2t-5x)$$. This wave gets reflected at a rigid boundary. The equation of the reflected wave is
  • $$y= A sin (2t-5x)$$
  • $$y= A sin (2t-5x +\pi)$$
  • $$y= A sin (2t+5x +\pi)$$
  • $$y= A sin (2t-5x +\pi/2)$$
The principle of superposition may be applied to waves whenever two (or more) waves travelling through different media have same frequency
  • True
  • False
Two waves represented by $$y_1=10\sin(2000\pi t)$$ and $$y_2=10\sin (2000 \pi t+\pi /2)$$ are superimposed at any point at a particular instant. The resultant amplitude is?
  • $$10$$ units
  • $$20$$ units
  • $$14.1$$ units
  • Zero
Reflection at a free boundary implies
  • restoring force is zero
  • restoring force is not zero
  • applied force is zero
  • applied force is not zero
A wave travelling on a string as shown in figure gets reflected at an open boundary. Then,
1015181_f13f25e9c20a4dc7a4685e84d78ca675.PNG
  • Phase reversal takes place at the boundary
  • Wavelength changes at the boundary
  • Phase reversal dosent take place
  • Speed of the reflected ray takes place
The angular frequency of a particle in a progressive wave in an elastic medium is $$100\pi\ { rads }^{ -1 }$$ and it is moving with a velocity of $$200{ms}^{-1}$$. The phase difference between two particles separated by a distance of $$20m$$ is:
  • $$31.4\ rad$$
  • $$\pi\ rad$$
  • $$\dfrac{3\pi}{4}\ rad$$
  • $$36\ rad$$
The equation of a progressive wave is given by $$y=10 sin (5t-x)$$. The wave gets reflected from a open boundary. The equation of the reflected wave is
  • $$y=10 sin (5t-x)$$
  • $$y=-10 sin (5t-x)$$
  • $$y=10 sin (5t+x)$$
  • $$y=10 sin (5t+x+\pi)$$
If $${y}_{1}=5(mm)]sin{\pi t}$$ and that of $${S}_{2}$$ is $${y}_{2}=5(mm)\sin{(\pi t+\pi /6)}$$. A wave from $${S}_{1}$$ reaches point A in $$1\ sec$$ while a wave from $${S}_{2}$$ reaches point A in $$0.5s$$. The resulting amplitude at point $$A$$ is :-
1023556_06bd1bbe68dd44c7bbf4ec4db562be22.PNG
  • $$5\sqrt { 2+\sqrt { 3 } } mm$$
  • $$5\sqrt { 3 } mm$$
  • $$5mm$$
  • $$5\sqrt { 2 }mm $$
Displacement time equation of  a particle executing SHM is x=4  sin$$\omega$$t + 3 sin ($$\omega t+ \dfrac{\pi}{3})$$ here x is in centimeter and t is in seconds . The amplitude of oscillation of the particle is approximately:
  • 5 cm
  • 6 cm
  • 7 cm
  • 9 cm

Two waves of frequencies 20 Hz and 30 Hz travels out from a common point. The phase difference between them after 0.6 sec is
  • $$12\pi $$
  • $${\pi \over 2}$$
  • $$\pi $$
  • $${{3\pi } \over 4}$$
The displacements of two particles executing $$SHM$$ on the same line are given as $$y_{1}=a\sin \left (\dfrac {\pi}{2}t+ \phi \right)$$ and $$y_{2}=b\sin \left (\dfrac {2\pi}{3}t+ \phi \right)$$. The phase difference between them at $$t=1\ s$$ is:
  • $$\pi$$
  • $$\dfrac {\pi }{2}$$
  • $$\dfrac {\pi }{4}$$
  • $$\dfrac {\pi}{6}$$
The displacement y of a particle varies with time t as $$y = 4 \sin\omega t\ \cos \omega t $$ cm where t is in seconds. The motion of the particle is
  • simple harmonic with amplitude 2 cm
  • simple harmonic with period $$\cfrac{\pi }{\omega } $$
  • simple harmonic with period $$\cfrac{2\pi }{\omega } $$
  • both a & b
A point source emits sound equally in all directions in a non-absorbing medium. Two points $$P$$ and $$Q$$ are at distance of $$2\ m$$ and $$3\ m$$ respectively from the source. The ratio of the intensities of the wave at $$P$$ and $$Q$$ is:
  • $$9:4$$
  • $$2:3$$
  • $$3:2$$
  • $$4:9$$
A wave pulse on a string has the dimension shown in figure. The wave speed is $$v=1\ cm/s$$. If point $$O$$ is a free end. The shape of wave at time $$t=3\ s$$ is
1032714_03db787ac966436f84d915e3a12191e3.png
Period of a particle performing S.H.M is 4 s. It starts motion from mean position. After 2/3 s, its velocity is 6.28 cm/s. The amplitude of S.H.M is:
  • (a) 8 cm
  • (b) $$\frac{4}{\sqrt{3}}$$
  • (c) $$\frac{8}{\sqrt{3}}$$
  • (d) 4 cm
Two coherent transverse waves of amplitude 2A and A of same frequency propagated respectively along $$+ve$$ and $$-ve$$ x-axis are superimposed. The amplitude of the resultant wave at a distance of 5 cm from the origin,$$(given K = \cfrac{\pi}{4}cm^{-1})$$ is
  • $$\sqrt{5A}$$
  • 4 A
  • 5 A
  • $$\sqrt{3A}$$
Two particles $$P$$ and $$Q$$ describe SHM of same amplitude $$a$$ and frequency $$f$$ along the same straight line. The maximum distance between two particles is $$a\sqrt{2}$$. The initial phase difference between the particles is:
  • $$\text {Zero}$$
  • $$\dfrac{\pi}{6}$$
  • $$\dfrac{\pi}{3}$$
  • $$\dfrac{\pi}{2}$$
Two waves of amplitudes $$A_0$$ and $$xA_0$$pass through a region.If $$x>1$$,what is the difference in the maximum and minimum resultant amplitude is :
  • $$(x+1)A_0$$
  • $$(x-1)A_0$$
  • $$2xA_0$$
  • $$2A_0$$
The amplitude of a wave disturbance propagating in the positive y-direction is given by:
$$y = \dfrac{1}{1 + x^2}$$ at $$ t = 0s \ and \ y = \dfrac{1}{1 + (x - 1)^2}$$ at $$ t = 2s$$, then wave velocity is
  • $$1 m/s$$
  • $$1.5 m/s$$
  • $$0.5 m/s$$
  • $$2 m/s$$
The light waves from two independent monochromatic light sources are given by-
$${y_1} = 2\sin  {\omega t }$$ and $${y_2} = 2\cos  {\omega t }$$,
then the following statement is correct 
  • Both the waves are coherent
  • Both the waves are incoherent
  • Both the waves have different time periods
  • None of the above
The displacement of a particle executing S.H.M is given by $$x=0.25sin200t$$in meters.The maximum speed of particle is :
  • $$50m{s^{ - 1}}$$
  • $$25m{s^{ - 1}}$$
  • $$200m{s^{ - 1}}$$
  • $$100m{s^{ - 1}}$$
The displacements of two interfering light waves are $$y_1 = 4 \ sin (\omega t) \ and \ y_2 = 3 \ cos (\omega t).$$ The amplitude of the resultant wave is ($$y_1$$ and $$y_2$$ are in CGS system)
  • $$5 cm$$
  • $$7 cm$$
  • $$1 cm$$
  • $$zero$$
The same progressive wave is represented by two graphs $$I$$ and $$II$$. Graph $$I$$ shows how the displacement $$'y'$$ varies with the distance $$x$$ along the wave at a given time. Graph $$II$$ shoes how $$y$$ varies with time $$t$$ at a given point on the wave. The ratio measurements $$AB$$ to $$CD$$, marked on the curves, represents:
1033615_c6c80a4700c94bf582833bf558182632.png
  • Wave number $$k$$
  • Wave speed $$V$$
  • Frequency $$v$$.
  • Angular frequency $$\omega$$
A body executing S.H.M has a maximum acceleration equal to $$48$$ m$$/\sec^2$$ and maximum velocity equal to $$12$$ m/$$\sec$$. The amplitude of S.H.M is?
  • $$3$$ m
  • $$3/32$$ m
  • $$1024/9$$ m
  • $$64/9$$ m
Two $$SHM$$ are represented by equation $$x_{1}=4\ \sin (\omega t+37^{o})$$ and $$x_{2}=5\ \cos (\omega t)$$. The phase difference between them is
  • $$37^{o}$$
  • $$127^{o}$$
  • $$53^{o}$$
  • $$143^{o}$$
A block is kept on a rough horizontal plank. The coefficient of friction between the block and the plank is 1/The plank is undergoing SHM of angular frequency 10 rad/s. The maximum amplitude of plank in which the block does not slip over the plank is ($$ g = 10 \ m/s^2$$)
  • $$4 cm$$
  • $$5 cm$$
  • $$10 cm$$
  • $$16 cm$$
Two sources of waves are called coherent if:-
  • Both have the same amplitude of vibrations
  • Both produce waves of the same wavelength
  • Both produce waves of the same wavelength having constant phase difference
  • Both produce waves having the same velocity
A particle is performing simple harmonic motion bout its equilibrium position $$X_0$$, then 
  • $$X_0$$ must be zero
  • velocity of particle at $$X_0$$ may be zero
  • acceleration of particle at $$X_0$$ may be zero
  • acceleration of particle at $$X_0$$ must be zero
from a line source, if amplitude of a wave at a a distance r is A, then the amplitude at a distance 4r will be 
  • 2A
  • A
  • A/2
  • A/4
Two waves of the same amplitude and frequency arrive at a point simultaneously. what should the phase difference between the waves so that amplitude of the resultant wave is double(2A) 
  • $$\dfrac {\pi}{2} radian$$
  • $$\dfrac {2\pi}{3} radian$$
  • $$\dfrac {3\pi}{4} radian$$
  • zero
The wavelength of the wave is:
  • $$6 \ cm$$
  • $$24 \ cm$$
  • $$12 \ cm$$
  • $$16 \ cm$$
A nylon guitar string has a linear density of $$7.20\ g/m$$ and is under tension of $$150\ N$$. The fixed supports are distance $$D= 90.0\ cm$$ apart. The string is oscillating in the standing wave pattern shown in figure.Calculate the
(ii) The wavelength of the traveling waves whose superposition gives this standing wave.
1116780_5c5467bdb1c4492e8ec1dc53f3c441b4.PNG
  • 20 cm
  • 40.0 cm
  • 60.0 cm
  • 80.0 cm
A particle performing simple harmonic motion along x-axis, with $$x = 0$$ as the mean position is released from rest at $$x = 2 cm$$ at $$t = 0$$. The time taken by particle in crossing the position $$x = 1.6cm$$ for the second time is: [Take amplitude of simple harmonic motion as $$2cm$$ and its period as $$1s$$]
  • $$\dfrac{1}{12}s$$
  • $$\dfrac{11}{12}s$$
  • $$\dfrac{323}{360}s$$
  • $$\dfrac{23}{66}s$$
A sine wave is travelling in a medium. A particular particle has zero displacement at a certain instant. the particle closest to it having zero displacement is at a distance
  • $$\lambda/4$$
  • $$\lambda/3$$
  • $$\lambda/2$$
  • $$\lambda$$
A particle moves along the X-axis according to the equation $$x = 10{\sin ^3}(\pi t)$$. the amplitudes and frequencies of component SHMs are
  • $$amplitude 30/4, 10/4; frequencies 3/2,1/2$$
  • $$amplitude 30/4 , 10/4; frequencies 1/2 , 3/2$$
  • $$amplitude 10 , 10 ; frequencies 1/2 , 1/2$$
  • $$amplitude 30/4 ,10 ; frequencies 3/2,2$$
A wave of frequency $$100$$ Hz is sent along a string towards a fixed end. When this wave travels back after reflection, a node is formed at a distance of $$10$$ cm from the fixed end of the string. The speeds of incident(and reflected) waves are?
  • $$5$$ $$cms^{-1}$$
  • $$10$$ $$cms^{-1}$$
  • $$20$$ $$cms^{-1}$$
  • $$40$$ $$cms^{-1}$$
Two periodic waves of amplitudes $$A_{1}$$ and $$A_{2}$$ pass through a region. If $$A_{1} > A_{2}$$, the difference in the maximum and minimum resultant amplitude possible is
  • $$2A_{1}$$
  • $$2A_{2}$$
  • $$A_{1}+A_{2}$$
  • $$A_{1}-A_{2}$$.
The maximum particle velocity is $$8$$ times the wave velocity of a progressive wave. If the amplitude of the particle is $$"a"$$. The phase difference between the two particles seperated by a distance of $$""x"$$ is 
  • $$\frac{x}{a}$$
  • $$\frac{{8x}}{a}$$
  • $$\frac{{3a}}{x}$$
  • $$\frac{{3\pi x}}{a}$$
The phase difference between two waves represented by 
$${y_1} = {10^{ - 6}}\sin \left[ {100t + \frac{x}{{50}} + 0.5} \right]m$$
$${y_2} = {10^{ - 6}}\cos \left[ {100t + \frac{x}{{50}}} \right]m$$
where x is expressed in metres and t is expressed in seconds is approximately
  • 1.07 rad
  • 2.07 rad
  • 0.5 rad
  • 1.5 rad
The displacement of a particle in SHM is $$x =3 sin(20\pi t) +4 cos (20\pi t)$$ cm.Its amplitude of oscillation is
  • 3 cm
  • 4 cm
  • 5 cm
  • 25 cm
Two identical sinusoidal waves each of amplitude $$5 mm$$ with a phase difference of $$\dfrac{\pi}{2}$$ are travelling in the same direction in a string. The amplitude of the resultant wave (in mm) is:-
  • Zero
  • $$5 \sqrt{2}$$
  • $$\dfrac{5} {\sqrt{2}}$$
  • $$2.5$$
A progressive wave moves with a velocity of $$36m/s$$ in a medium with a frequency of $$200Hz$$. The phase difference between two particles separated by a distance of $$1cm$$ is:
  • $${40 }$$ 
  • $$20$$ 
  • $$\dfrac{\pi }{9}$$ 
  • $$\dfrac{{{\pi  }}}{16}$$ 
The value of phase, at maximum displacement from the mean position of a particle, in SHM is ?
  • $$\dfrac{\pi} {2}$$
  • $$\pi $$
  • zero
  • $$2\pi $$
0:0:1


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