CBSE Questions for Class 11 Engineering Physics Waves Quiz 7 - MCQExams.com

If two waves of same frequency and amplitude respectively on superposition produce a resultant disturbance of the same amplitude, the wave differ in phase by :
  • $$\pi $$
  • zero
  • $$\pi /3$$
  • $$2\pi /3 $$
The displacement of a particle varies according to the relation $$x=4(\cos {\pi t}+\sin {\pi t})$$. The amplitude of the particle is:
  • $$-4$$
  • $$4$$
  • $$4\sqrt {2}$$
  • $$8$$
A progressive wave of frequency $$500\  Hz$$ is travelling with a speed of $$330\  m/s$$ in air. The distance between the two points which have a phase difference of $$\displaystyle { 30 }^{ \circ  }$$ is:
  • $$0.11\  m$$
  • $$0.055 \ m$$
  • $$0.22\  m$$
  • $$0.025\  m$$
In a medium in which, a transverse progressive wave travelling, the phase difference between the points with a separation of $$1.25\  cm$$ is $$\displaystyle { \pi  }/{ 4 }$$. If the frequency of wave $$1000\  Hz$$, the velocity in the medium is :
  • $$\displaystyle { 10 }^{ 4 }\ { ms }^{ -1 }$$
  • $$\displaystyle 125\ { ms }^{ -1 }$$
  • $$\displaystyle 100\ { ms }^{ -1 }$$
  • $$\displaystyle 10\ { ms }^{ -1 }$$
Find out the change in wavelength of a $$700 Hz$$ acoustic wave as it enters brass from warm air? Given Speed of Sound in warm air is  $$350 {m}/{s}$$ and through brass is $$3,500 {m}/{s}$$.
  • It decreases by a factor of $$20$$
  • It decreases by a factor of $$10$$
  • It increases by a factor of $$10$$
  • It increases by a factor of $$20$$
  • The wavelength remains unchanged when a wave passes into a new medium
Five sinusoidal waves have the same frequency $$500Hz$$ but their amplitudes are in the ratio $$2:\cfrac{1}{2}:\cfrac{1}{2}:1:1$$ and their phase angles $$0,\cfrac{\pi}{6},\cfrac{\pi}{3},\cfrac{\pi}{2}$$ and $$\pi$$ respectively. The phase angle of resultant wave obtained by the superposition of these five waves is:
  • $${30}^{o}$$
  • $${45}^{o}$$
  • $${60}^{o}$$
  • $${90}^{o}$$
If n represents the order of a half period zone the area of this zone is approximately proportional to $$n^{m}$$ where m is equal to
  • zero
  • half
  • one
  • two
Two simple harmonic motions are given by:
$$ { x }_{ 1 }=a\sin { \omega t } +a\cos { \omega t } $$
$${ x }_{ 2 }=a\sin { \omega t } +\cfrac { a }{ \sqrt { 3 }  } \cos { \omega t } $$
The ratio of the amplitudes of first and second motion and the phase difference between them are respectively:
  • $$\sqrt { \cfrac { 3 }{ 2 } } $$ and $$\cfrac { \pi }{ 12 } $$
  • $$\cfrac { \sqrt { 3 } }{ 2 } $$ and $$\cfrac { \pi }{ 12 } $$
  • $$\cfrac { 2 }{ \sqrt { 3 } } $$ and $$\cfrac { \pi }{ 12 } $$
  • $$\sqrt { \cfrac { 3 }{ 2 } } $$ and $$\cfrac { \pi }{ 6 } $$
A pulse of a wave travelling on a string towards the fixed rigid end as shown in the figure above. The pulse is:
480280_8e30a8d0c735472cb780798608b9df8c.png
  • Reflected and transmitted
  • Reflected and refracted
  • Reflected and reduced
  • Reflected and magnified
  • Reflected and inverted
State whether the given statement is True or False :
If the distance between two successive troughs in a transverse wave is $$8 cm$$, then the amplitude of that wave is $$4 cm$$.
  • True
  • False
A particle in SHM is described by the displacement function: $$x(t)= A \ cos (\omega t+ \phi).$$ If the initial (t=0) position of the particle is 1 cm and its initial velocity is $$\pi $$ cm/sec , what is the amplitude?
  • $$\sqrt 2 cm $$
  • $$ 2 cm $$
  • $$\sqrt 7 cm $$
  • $$12 cm $$
A particle in SHM is described by the displacement function: $$x(t)= A \ cos (\omega t+ \phi).$$ If the initial $$(t=0)$$ position of the particle is $$1$$ cm and its initial velocity is $$\omega $$ cm/sec , what is the initial phase angle ?
  • $$\dfrac{3\pi}{4}$$
  • $$\dfrac{7 \pi}{4}$$
  • $$\dfrac{7 \pi}{2}$$
  • $$\dfrac{\pi}{4}$$
The wave carries ______________
  • Power
  • Energy
  • Displacement
  • Work
The frequency of a sound wave is 200 Hz and its wavelength is 150 cm.  What is the distance travelled by the sound wave in the time taken to produce 150 waves?
  • 110 cm
  • 225 cm
  • 112.5 cm
  • 336.5 cm
Two travelling waves of equal frequency, with amplitude $$4 cm$$ and $$6 cm$$ respectively, superimpose in a single medium. Find out the range of the amplitude, $$A$$, of the resultant wave?
  • $$2 cm \leq A \leq 10 cm$$
  • $$A = 5 cm$$
  • $$A = 10 cm$$
  • $$10 cm \leq A \leq 12 cm$$
  • $$12 cm \leq A \leq 24 cm$$
Two simple harmonic motions are given by
$$x_1 = a \sin \omega t + a \cos \omega t$$ and
$$x_2 = a \sin \omega t + \dfrac{a}{\sqrt{3}}\cos \omega t$$
The ratio of the amplitudes of first and second motion and the phase difference between them are respectively
  • $$\sqrt{\dfrac{3}{2}}$$ and $$\dfrac{\pi}{12}$$
  • $${\dfrac{\sqrt{3}}{2}}$$ and $$\dfrac{\pi}{12}$$
  • $${\dfrac{3}{\sqrt{2}}}$$ and $$\dfrac{\pi}{12}$$
  • $$\sqrt{\dfrac{3}{2}}$$ and $$\dfrac{\pi}{6}$$
An excerpt from a book by Einstein and Infeld gives the following remarks concerning wave phenomena:
"A bit of gossip starting in Washington reaches New York [by word of mouth] very quickly, even though not a single individual who takes part in spreading it travels between these two cities. There are two quite different motions involved, that of the rumor, Washington to New York, and that of the persons who spread the rumor."

Identify a correct inference from the above text.
  • The particles of the medium perform motion from one place to another.
  • The particles of the medium perform random motion to constitute wave motion.
  • The particles constituting the medium perform only small vibrations, but the whole motion is that of a progressive wave.
  • None of these.
The S.I unit of wavelength is ______________
  • $$cm$$
  • $$dm$$
  • $$m$$
  • $$km$$
During the propagation of wave motion, 
  • there is transfer of energy from one particle to another without any actual transfer of the particles of the medium.
  • there is transfer of energy from one particle to another with transfer of the particles of the medium.
  • there is no transfer of energy from one particle to another.
  • None of these.
Identify the correct statement:
  • The power of ripples in water is much greater than the power of sound waves generated by a single human voice.
  • The power of ocean waves during a storm is much greater than the power of sound waves generated by a single human voice.
  • The power of sound waves generated by a single human voice is much greater than the power of ocean waves during a storm.
  • All statements are wrong.
Which of the following is a Longitudinal wave? _____________
  • Radio wave
  • X-rays
  • Light waves
  • Sound waves
As waves propagate through a medium, they transport energy. We can easily demonstrate this by 
  • hanging an object on a stretched string and then sending a pulse down the string
  • throwing a stone into a pond
  • compressing a spring and releasing it.
  • None of these.
Three waves of amplitudes $$ 12\mu m $$, $$ 4\mu m $$ and $$ 9\mu m $$ but of same frequency arrive at a point in a medium with a successive phase diffeerence  of $$\dfrac{\pi}{2}$$. Then the resultant amplitude is
  • $$4$$
  • $$7$$
  • $$5$$
  • $$25$$
The displacement y of a wave traveling in the X-direction is given by $$y = 10^{-4}\sin({600t-2x+\dfrac{\pi}{3})}$$ metres. where $$x$$ is expressed in metres and $$t$$ in $$seconds$$. The speed of the wave motion in $$ms^{-1}$$ is:
  • $$200$$
  • $$300$$
  • $$600$$
  • $$1200$$
A traveling wave in a stretched string is described by the equation, $$y = A \sin(kx+t)$$. The maximum particle velocity is
  • A
  • $$k$$
  • $$Ak$$
  • none of the above
A weight of 5 kg is required to produce the fundamental frequency of a sonometer wire. What weight is required to produce its octave?
  • 20
  • 32
  • 26
  • none of the above
A stationary wave is a multidimensional variant depending on
  • time axis
  • position axis
  • time and position axis
  • none of the above
Two sound waves each of amplitude $$a$$ and of frequencies $$500 Hz$$ and $$512 Hz$$ superpose. Then the resultant of the amplitude of the resultant wave at $$t=\dfrac{5}{48} s$$ is
  • $$0$$
  • $$\dfrac { a }{ \sqrt { 2 } } $$
  • $$a\sqrt { 2 } $$
  • $$2a$$
If two waves of length $$50 cm$$ and $$51 cm$$ produced $$12$$ beats $$per\ second$$, the velocity of sound is:
  • $$360$$
  • $$340$$
  • $$306$$
  • none of the above
A stationary wave is represented by the equation, $$y = 3 \cos(x/8) \sin(15t)$$ where $$x$$ and $$y$$ are in $$cm$$ and $$t$$ is in $$seconds$$. The distance between the consecutive nodes is (in $$cm$$):
  • $$8$$
  • $$12$$
  • $$14$$
  • $$16$$
Two points on a travelling wave having frequency $$500 Hz$$ and velocity $$300{ m }/{ s }$$ are $${ 60 }^{ o }$$ out of phase, then the minimum distance between the two points is
  • $$0.2$$
  • $$0.1$$
  • $$0.5$$
  • $$0.4$$
Sum of two mechanical waves travelling in any direction (having the same frequency),
  • can be summed up to give a stationary wave
  • is added using the phasor diagram
  • can have graphical representation with no troughs and elevations
  • none of the above
Stethoscope of doctors for finding quality, strength and frequency of human heart beat is based on the principle of
  • SONAR
  • Reverberation
  • Multiple reflection
  • Echo
A progressive wave is represented by y = 12 sin (5t - 4x) cm. On this wave, how far away are the two points having phase difference of 90$$^o$$?
  • $$\dfrac{\pi}{2} cm$$
  • $$\dfrac{\pi}{4} cm$$
  • $$\dfrac{\pi}{8} cm$$
  • $$\dfrac{\pi}{16} cm$$
On watching the graphical representation of different waves which of the following does not have energy carrying capacity
  • Electromagnetic waves
  • Stationary waves
  • Unidirectional travelling string wave
  • none of the above
The equation of a simple harmonic wave is given by $$y = 6 \sin{2\pi} \left(2t-0.1x\right)$$, where $$x$$ and $$y$$ are in $$mm$$ and $$t$$ is in seconds. The phase difference between two particles $$2 mm$$ apart at any instant is
  • $${18}^{o}$$
  • $${36}^{o}$$
  • $${54}^{o}$$
  • $${72}^{o}$$
The amplitude of resulting wave dues to superposition of $$y_1 = A sin (t -kx)$$ & $$y_2 = A sin (t -kx + \delta)$$ is
  • $$2A cos(\delta/2)$$
  • $$2A tan (\delta/2)$$
  • $$A \cos (\delta /2)$$
  • none
 The amplitude of resulting wave dues to superposition of $$y_1 = A sin (t -kx)$$ & $$y_2 = A sin (t- kx + \delta)$$ is
  • $$2A cos(\delta/2)$$
  • $$2A tan (\delta/2)$$
  • $$A cos(\delta/2)$$
  • none
The path difference between two waves
$$y_{1} = a_{1}\sin \left (\omega t - \dfrac {2\pi x}{\lambda}\right )$$ and
$$y_{2} = a_{2}\cos \left (\omega t - \dfrac {2\pi x}{\lambda} +\phi \right )$$ is
  • $$\dfrac {\lambda \phi}{2\pi}$$
  • $$ \dfrac{\lambda}{2\pi} (\dfrac {\pi}{2} + \phi)$$λϕ2π(ϕ+π2)
  • $$ \dfrac{\lambda}{2\pi} (\dfrac {\pi}{2} - \phi)$$λϕ2π(ϕ−π2)
  • $$\dfrac {2\pi \phi}{\lambda}$$
The minimum phase difference between two simple harmonic oscillations,
$$y_1  = \dfrac{1}{2} sim \omega t + \dfrac{\sqrt 3}{2} cos \omega t$$
$$y_2 = sim \omega t + cos \omega t$$, is
  • $$\dfrac{7\pi}{12}$$
  • $$\dfrac{\pi}{12}$$
  • $$\dfrac{-\pi}{6}$$
  • $$\dfrac{\pi}{6}$$
A particle performing S.H.M. starts from equilibrium position and its time period is $$16$$ second. After $$2$$ seconds its velocity is $$\pi \ m/s$$. Amplitude of oscillation is $$(\cos 45^{\circ} = \dfrac {1}{\sqrt {2}})$$
  • $$2\sqrt {2} m$$
  • $$4\sqrt {2}m$$
  • $$6\sqrt {2} m$$
  • $$8\sqrt {2}m$$
Two sound waves having a phase difference of $$60^o$$, have a path difference of :
  • $$\dfrac{\lambda}{3}$$
  • $$\dfrac{\lambda}{6}$$
  • $$\dfrac{\lambda}{9}$$
  • $$\lambda$$
A simple harmonic wave of amplitude $$8$$ unit travels along positive $$x$$-axis. At any given instant of time, for a particle at a distance of $$10 cm$$ from the origin, the displacement is $$+6$$ unit and for a particle at a distance of $$25 cm$$ from the origin, the displacement is $$+4$$ unit. Calculate the wavelength.
  • $$200 cm$$
  • $$230 cm$$
  • $$210 cm$$
  • $$250 cm$$
Two particles A and B execute simple harmonic motions of periods T and 5T /They start from mean position. The phase difference between them when the particle A complete one oscillation will be:
  • $$0$$
  • $$\dfrac{\pi}{2}$$
  • $$\dfrac{2\pi}{5}$$
  • $$\dfrac{\pi}{6}$$
The phenomena during arising due to the superstition of waves is/are :
  • Beats
  • Stationary waves
  • Lissajous figures
  • All of these
Two particles P and Q describe SHM of same amplitude a frequency v along the same straight line. The maximum distance between two particles is $$\displaystyle \sqrt { 2a } $$. The initial phase difference between the particles is :
  • Zero
  • $$\displaystyle { \pi }/{ 2 }$$
  • $$\displaystyle { \pi }/{ 6 }$$
  • $$\displaystyle { \pi }/{ 3 }$$
A progressive wave is represented as $$y=0.2\cos \pi (0.04 t+0.2x-\dfrac{\pi}{6})$$ where distance is expressed in cm and time in second. What will be the minimum distance between two particles having the phase difference of $$\dfrac{\pi}{2}$$?
  • 4 cm
  • 8 cm
  • 25 cm
  • 12.5 cm
With the propagation of a longitudinal wave through a material medium the quantities transmitted in the propagation direction are
  • Energy, momentum and mass
  • Energy
  • Energy and mass
  • Energy and linear momentum
At a moment in a progressive wave, the phase of a particle executing SHM is $$\dfrac {\pi}{3}$$. Then the place of the particle $$15\ cm$$ ahead and at time $$\dfrac {T}{2}$$ will be, if the wavelength is $$60\ cm$$.
  • Zero
  • $$\dfrac {\pi}{2}$$
  • $$\dfrac {5\pi}{6}$$
  • $$\dfrac {2\pi}{3}$$
Equations of a stationary and a travelling waves are as follows, $${ y }_{ 1 }=a\sin { kx } \cos { \omega t } $$ and $${ y }_{ 2 }=a\sin { \left( \omega t-kx \right)  }$$. The phase difference between two points $${ x }_{ 1 }=\dfrac { \pi  }{ 3k } $$ and $${ x }_{ 2 }=\dfrac { 3\pi  }{ 2k } $$ are $${ \phi  }_{ 1 }$$ and $${ \phi  }_{ 2 }$$ respectively for two waves. The ratio $$\dfrac { { \phi  }_{ 1 } }{ { \phi  }_{ 2 } } $$ is :
  • $$1$$
  • $${ 5 }/{ 6 }$$
  • $${ 3 }/{ 4 }$$
  • $${ 6 }/{ 7 }$$
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