CBSE Questions for Class 11 Engineering Physics Waves Quiz 1 - MCQExams.com

A transverse wave travels on a taut steel wire with a velocity of $$v$$ when the tension in it is $$2.06\times { 10 }^{ 4 }N$$. When the tension is changed to $$T$$, the velocity changed to $$v/2$$. The value of $$T$$ is closet to:
  • $$2.50\times { 10 }^{ 4 }N$$
  • $$10.2\times { 10 }^{ 2 }N$$
  • $$30.5\times { 10 }^{ 4 }N\quad $$
  • $$5.15\times { 10 }^{ 3 }N$$
The displacement of a particle varies according to the relation $$x = 4(\cos \pi t + \sin \pi t)$$. The amplitude of the particle is
  • $$-4$$
  • $$4$$
  • $$4\sqrt{2}$$
  • $$8$$
Amplitude of a wave is represented by $$A = \dfrac {c}{a + b - c}$$. Then resonance will occur when
  • $$b = -c/ 2$$
  • $$b = 0$$ and $$a = c$$
  • $$b = -a/2$$
  • None of the above
A simple wave motion represented by $$y=5(\sin 4\pi t+\sqrt 3 \cos 4\pi t)$$. Its amplitude is:
  • $$5$$
  • $$5\sqrt 3$$
  • $$10\sqrt 3$$
  • $$10$$
The phase change between incident and reflected sound wave from a free end is
  • $$0$$
  • $$\pi $$
  • $$3\pi $$
  • $$2\pi $$
Which of the following is conserved when light waves interfere?
  • momentum
  • amplitude
  • energy
  • intensity
Phase difference between a particle at a compression and a particle at the next rarefaction is
  • Zero
  • $$\dfrac{\pi}{2}$$
  • $$\pi$$
  • $$\dfrac{\pi}{4}$$
Thickness of very thin films can be found by the technique of
  • Dispersion
  • Interference
  • polarization
  • Diffraction
Two light waves are represented by $$y_{1}=4\sin  \omega t$$ and $$y_{2}= 3\sin(\omega t+\frac{\pi }{2} ) $$ . The resultant amplitude due to interference will be
  • $$5cm$$
  • $$7cm$$
  • $$1cm$$
  • $$0$$
For the sustained interference of light, the necessary condition is that the two sources should
  • have constant phase difference only
  • be narrow
  • be close to each other
  • of same amplitude with constant phase difference
The necessary condition for an interference by two sources of light is that: 
  • two light sources must have the same wavelength
  • two point sources should have the same amplitude and same wavelength
  • two sources should have the same wavelength, nearly the same amplitude and have a constant phase angle difference
  • the two point sources should have a randomly varying phase difference
Four different independent waves are represented by
a) $$ y_{1}=a_{1} \sin  \omega  _{1}t$$
b) $$ y_{2}=a_{2} \sin \omega  _{2}t$$
c) $$y_{3}=a_{3} \sin \omega  _{3}t$$
d) $$y_{4}=a_{4} \sin (\omega _{4} t + \pi  /3)$$
The sustained interference is possible due to
  • a & c
  • a & d
  • c & d
  • Not possible with any combination
The phase difference between the particle at one compression and another particle in third compression is
  • $$\pi $$ radians
  • $$2\pi $$ radians
  • $$3\pi $$ radians
  • $$4\pi $$ radians
When viewed in white light, soap bubble show colors because of
  • Interference
  • Scattering
  • Diffraction
  • Dispersion
If a wave completes 24 cycles in 0.8 s, then frequency of the wave is
  • 30 Hz
  • 8 Hz
  • 24 Hz
  • 12 Hz
For superposition of two waves, which of the following is correct
  • They must have the same frequency and wavelength
  • They must have equal frequencies but may have unequal wavelengths
  • They must have the same wave-length, but may have different frequencies
  • They may have different wavelength and different frequencies
If the frequency of a wave is doubled, then its wavelength
  • Becomes doubled
  • Remains same
  • Becomes half of the original
  • None of these
A wave creates disturbance and transmits matter from one place to another.
  • True
  • False
Speed of sound wave in a given medium is
  • Directly proportional to its frequency
  • Inversely proportional to its frequency
  • Directly proportional to the square of frequency
  • Independent of its frequency
The interference phenomenon can take place
  • in transverse wave
  • in longitudinal wave
  • in electromagnetic waves
  • in all waves
The disturbance caused in a medium is called
  • Straight line
  • Wave
  • Disturbance
  • None of these
The product of the time period of a wave and its frequency is
  • Infinite
  • Zero
  • More than unity but less than infinity
  • Unity
Which of the following quantity decrease as sound wave travels through a medium :
  • Amplitude
  • Frequency
  • Velocity
  • Wavelength

Two waves $${y_1} = {A_1}\sin (\omega t - {\beta _1}){y_2} = {A_2}\sin (\omega t - {\beta _2})$$ superimpose to form a resultant wave whose amplitude is
  • $$\sqrt {A_1^2 + A_2^2 + 2{A_1}{A_2}\cos ({\beta _1} - {\beta _2})} $$
  • $$\sqrt {A_1^2 + A_2^2 + 2{A_1}{A_2}\sin ({\beta _1} - {\beta _2})} $$
  • $$A_1 + A_2$$
  • $$|A_1 + A_2|$$
When two plane progressive waves travelling in same direction superimpose over each other, the velocity of the resultant wave will
  • increase
  • remain unchanged
  • be zero
  • decrease
What will be the wave velocity, if the radar gives 54 waves per min and wavelength of the given wave is 10 m?
  • 4 m s$$^{-1}$$
  • 6 m s$$^{-1}$$
  • 9 m s$$^{-1}$$
  • 5 m s$$^{-1}$$
The particle of a medium vibrates about their mean position whenever a wave travels through that medium. The phase difference between the vibrations of two such particles
  • varies with time only
  • varies with distance separating them only
  • varies with time as well as distance
  • is always zero
An ultrasonic source emits sound of frequency 220 kHz in air. If this sound meets a water surface, what is the wavelength of the reflected sound?
  • $$1.6 \times 10^{-3} m$$
  • $$2.6 \times 10^{-3} m$$
  • $$3.6 \times 10^{-3} m$$
  • $$4.6 \times 10^{-3} m$$
A piezo - electric quartz plate is vibrating to produce wavelength of $$10^{-1}$$ m. Find the frequency if for quartz $$Y=8 \times 10^{10} N  m^{-2}$$ and $$\rho = 2.65 \times 10^3  kg  m^{-3}$$
  • 350 kHz
  • 450 kHz
  • 550 kHz
  • 650 kHz
The frequency of a man's voice is $$300\space Hz$$. If the velocity of sound waves is $$336\space ms^{-1}$$, the wavelength of the sound is
  • $$1.12\space m$$
  • $$300\times336\space m$$
  • $$330/336\space m$$
  • None of these
In ordinary talk, the amplitude of vibration is approximately:
  • $$10^{-12} m $$
  • $$10^{-11} m $$
  • $$10^{-8} m $$
  • $$10^{-7} m $$
The frequency, wavelength and speed of a sound wave are related as :
$$v=velocity\ of\ wave,\ u=frequency,\ \lambda=wavelength $$
  • $$\lambda=vT$$
  • $$\lambda=v/u$$
  • $$u=v/\lambda$$
  • $$\lambda=uv$$
The phenomenon of interference is shown by 
  • longitudinal mechanical waves only
  • transverse mechanical waves only
  • non mechanical transverse waves only
  • all the above types of waves
Two waves represented by $$y_1= a sin\omega t $$ and $$ y_2 = a sin(\omega t+ \phi) $$ and  $$ \phi =\dfrac{\pi}{2} $$ are superposed at any point at a particular instant. The resultant amplitude is
  • $$ a$$
  • $$4a$$
  • $$\sqrt{2} a$$
  • $$zero$$

The picture shows a wave generated in a laboratory. What is the amplitude of the wave shown ?
283902_fa2da311b33c4bfb96445a7a6355686f.png
  • 0.85 cm
  • 1.7 cm
  • 2.7 cm
  • There is not enough information to determine the answer.
The velocity of sound in a gas is 4 times that in air at the same temperature. When a tuning fork is sounded in a wave of frequency 480 and wavelength $$\lambda_1$$ is produced. The same fork is sounded in the gas and of $$\lambda_2$$ is the wavelength of the wave, then $$\lambda_2\,/\, \lambda_1$$ is :
  • 1
  • 2
  • 4
  • 1/2
In the following properties of a wave, the one which is independent of the other is
  • amplitude
  • velocity
  • wavelength
  • frequency
'Which is not true for a wave ?
  • Wave velocity v = n$$\lambda$$
  • Energy is transferred during wave motion
  • All waves can pass through vacuum
  • Unit of wave velocity is $$m/s$$
Time period of a sound wave having the wavelength $$0.2 m$$ and frequency $$10$$ Hz will be
  • $$2s$$
  • $$0.2s$$
  • $$0.1s$$
  • $$0.02s$$
The stethoscope used by doctors works on the principle of 
  • Refraction of sound
  • Reflection of sound
  • Interference of sound
  • Absorption of sound
The SI unit of amplitude of oscillation is :
  • $$cm$$
  • $$m$$
  • $$km$$
  • $$\mu m$$
A source of frequency $$500   Hz$$ emits waves of wavelength $$0.2  \  m$$. The time the wave takes to travel a distance of $$300\    m$$ is :
  • 75 seconds
  • 60 seconds
  • 12 seconds
  • 3 seconds
The maximum displacement of the particles of a medium in which a wave is travelling is called _________ .
  • amplitude
  • frequency
  • beat
  • phase
Two particles having the same phase must be at
  • one crest and one trough
  • one crest and the mean position
  • one trough and the mean position
  • two consecutive crests
Light : Ray : : Sound : ?
  • Hear
  • Wave
  • Audio
  • Pitch
The relation between frequency $$(n)$$ and wavelength $$(\lambda)$$ of a sound wave is given by 
($$v$$ is velocity, $$n$$ is frequency and $$T$$ is time-period)
  • $$v=n\lambda$$
  • $$n=-v\lambda$$
  • $$v=\displaystyle\frac{n}{2\lambda}$$
  • $$n=\displaystyle\frac{T}{\lambda }$$
Two particles having the same phase must be at
  • a crest and a trough respectively at the same time
  • a crest and at the mean position respectively at the same time
  • a trough and at the mean position respectively at the same time
  • Two consecutive crests respectively at the same time
If the maximum acceleration of the body executing S.H.M. is a$$_0$$ and maximum velocity is V$$_0$$ the amplitude is given by
  • $$\displaystyle \frac{1}{a_0 v_0}$$
  • $$\displaystyle \frac{a_0}{v_0}$$
  • $$v_0 a_0$$
  • $$\displaystyle \frac{v_0^2}{a_0}$$
What type of wave travels the faster?
  • Sound
  • Earthquake
  • Ocean
  • Light
Frequency $$(v)$$ and time period $$(T)$$ of a sound wave are related as :
  • $$v\times T=1$$
  • $$\displaystyle\frac{v}{T}=1$$
  • $$v\times T^2$$
  • $$v=T^{-2}$$
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