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Physics M.C.Q (1 Marks)

Wave Optics · Rajasthan Board (RBSE) STD 12 Science (Rajasthan - English Medium). 397 questions.

Questions · Page 3 of 8

M.C.Q (1 Marks)

MCQ 1011 Mark
The 21 cm radio wave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction is atomic hydrogen. the energy of the emitted wave is nearly
  • A
     $10^{-17}$ Joule
  • B
     $1$ Joule
  • C
     $7 \times 10^{-8}$ Joule
  • ✓
     $10^{-24}$ Joule
Answer
Correct option: D.
 $10^{-24}$ Joule
$10^{-24}$ Joule
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MCQ 1021 Mark
In an electromagnetic wave, the electric and magnetising fields are $100 Vm ^{-1}$ and $0.265 Am ^{-1}$. The maximum energy flow is
  • ✓
     $26.5 W / m ^2$
  • B
     $36.5 W / m ^2$
  • C
     $46.7 W / m ^2$
  • D
    $765 W / m ^2$
Answer
Correct option: A.
 $26.5 W / m ^2$
$26.5 W / m ^2$
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MCQ 1031 Mark
According to Maxwell’s hypothesis, a changing electric field gives rise to
  • A
    An e.m.f.
  • B
     Electric current
  • ✓
     Magnetic field
  • D
    Pressure radiant
Answer
Correct option: C.
 Magnetic field
Magnetic field
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MCQ 1041 Mark
In the adjacent diagram, CP represents a wavefront and AO & BP, the corresponding two rays. Find the condition on q for constructive interference at P between the ray BP and reflected ray OP
  • A
    cosq = 3l/2d
  • ✓
    cosq = l/4d
  • C
    secq – cosq = l/d
  • D
    secq – cosq = 4l/d
Answer
Correct option: B.
cosq = l/4d
(b) cosq = l/4d
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MCQ 1051 Mark
A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plate as shown. The observed interference fringes from this combination shall be
  • ✓
    Straight
  • B
    Circular
  • C
    Equally spaced
  • D
    Having fringe spacing which increases as we go outwards
Answer
Correct option: A.
Straight
(a) Straight
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MCQ 1061 Mark
A ray of light of intensity I is incident on a parallel glass-slab at a point A as shown in fig. It undergoes partial reflection and refraction. At each reflection 25% of incident energy is reflected. The rays AB and A'B' undergo interference. The ratio $\mathrm{I}_{\max } / \mathrm{I}_{\min }$ is
  • A
    4 : 1
  • B
    8 : 1
  • C
    7 : 1
  • ✓
    49 : 1
Answer
Correct option: D.
49 : 1
(d) 49 : 1
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MCQ 1071 Mark
Light wave is travelling along y-direction. If the corresponding $\vec E$ vector at any time is along the x-axis, the direction of $\vec B$ vector at that time is along
  • A
    y-axis
  • B
    x-axis
  • C
    + z-axis
  • ✓
    – z axis
Answer
Correct option: D.
– z axis
(d) – z axis
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MCQ 1081 Mark
Which one of the following is not electromagnetic in nature
  • A
     X-rays
  • B
    Gamma rays
  • ✓
    Cathode rays
  • D
     Infrared rays
Answer
Correct option: C.
Cathode rays
 Cathode rays
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MCQ 1091 Mark
If $\vec{E}$ and $\vec{B}$ are the electric and magnetic field vectors of E.M. waves then the direction of propagation of E.M. wave is along the direction of
  • A
     $\vec{E}$
  • B
     $\vec{B}$
  • ✓
     $\vec{E} \times \vec{B}$
  • D
    None of these
Answer
Correct option: C.
 $\vec{E} \times \vec{B}$
 $\vec{E} \times \vec{B}$
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MCQ 1101 Mark
Infrared radiation was discovered in 1800 by
  • A
    William Wollaston
  • ✓
    William Herschel
  • C
    Wilhelm Roentgen
  • D
    Thomas Young
Answer
Correct option: B.
William Herschel
 William Herschel
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MCQ 1111 Mark
The pressure exerted by an electromagnetic wave of intensity I (watts/$\mathrm{m}^2$) on a nonreflecting surface is [c is the velocity of light]
  • A
    Ic
  • B
    Ic$^2$
  • ✓
    I/c
  • D
    I/c$^2$
Answer
Correct option: C.
I/c
(c) I/c
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MCQ 1121 Mark
For skywave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
  • ✓
    $\sim 1.2 \times 10^{12} m^{-3}$
  • B
     $\sim 10^6 m^{-3}$
  • C
    $~ 10^{14} m^{-3}$
  • D
    $\sim 10^{22} m^{-3}$
Answer
Correct option: A.
$\sim 1.2 \times 10^{12} m^{-3}$
$\sim 1.2 \times 10^{12} m^{-3}$
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MCQ 1131 Mark
An optically active compound
  • ✓
    Rotates the plane polarised light
  • B
     Changing the direction of polarised light
  • C
     Do not allow plane polarised light to pass through
  • D
    None of the above
Answer
Correct option: A.
Rotates the plane polarised light
Rotates the plane polarised light
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MCQ 1141 Mark
Electromagnetic waves travel in a medium which has relative permeability 1.3 and relative permittivity 2.14 . Then the speed of the electromagnetic wave in the medium will be
  • A
     $13.6 \times 10^6 m / s$
  • B
     $1.8 \times 10^2 m / s$
  • C
     $3.6 \times 10^8 m / s$
  • ✓
     $1.8 \times 10^8 m / s$
Answer
Correct option: D.
 $1.8 \times 10^8 m / s$
 $1.8 \times 10^8 m / s$
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MCQ 1151 Mark
When unpolarised light beam is incident from air onto glass (n = 1.5) at the polarising angle
  • ✓
     Reflected beam is polarised 100 percent
  • B
     Reflected and refracted beams are partially polarised
  • C
     The reason for (a) is that almost all the light is reflected
  • D
     All of the above
Answer
Correct option: A.
 Reflected beam is polarised 100 percent
Reflected beam is polarised 100 percent
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MCQ 1161 Mark
Electromagnetic waves are transverse in nature is evident by
  • ✓
    Polarization
  • B
    Interference
  • C
     Reflection
  • D
    Diffraction
Answer
Correct option: A.
Polarization
 Polarization
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MCQ 1171 Mark
Which of the following waves have the maximum wavelength
  • A
    X-rays
  • B
    I.R. rays
  • C
    UV rays
  • ✓
    Radio waves
Answer
Correct option: D.
Radio waves
Radio waves
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MCQ 1181 Mark
The region of the atmosphere above troposphere is known as
  • A
     Lithosphere
  • B
    Uppersphere
  • C
    Ionosphere
  • ✓
    Stratosphere
Answer
Correct option: D.
Stratosphere
 Stratosphere
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MCQ 1191 Mark
Which of the following shows green house effect
  • A
    Ultraviolet rays
  • ✓
    Infrared rays
  • C
    X-rays
  • D
    None of these
Answer
Correct option: B.
Infrared rays
 Infrared rays
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MCQ 1201 Mark
An electromagnetic wave of frequency v = 3.0MHz passes from vacuum into a dielectric medium with permittivity ε = 4.0 . Then
  • A
     Wavelength is doubled and the frequency remains unchanged
  • B
     Wavelength is doubled and frequency becomes half
  • ✓
     Wavelength is halved and frequency remains unchanged
  • D
     Wavelength and frequency both remain unchanged
Answer
Correct option: C.
 Wavelength is halved and frequency remains unchanged
 Wavelength is halved and frequency remains unchanged
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MCQ 1211 Mark
The wavelength 21 cm emitted by atomic hydrogen in interstellar space belongs to
  • ✓
     Radio waves
  • B
    Infrared waves
  • C
    Microwaves
  • D
     g-rays
Answer
Correct option: A.
 Radio waves
Radio waves
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MCQ 1221 Mark
Electromagnetic radiation of highest frequency is
  • A
     Infrared radiations
  • B
     Visible radiation
  • C
    Radio waves
  • ✓
    g-rays
Answer
Correct option: D.
g-rays
g-rays
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MCQ 1231 Mark
Television signals broadcast from the moon can be received on the earth while the TV broadcast from Delhi cannot be received at places about 100 km distant from Delhi. This is because
  • A
    There is no atmosphere around the moon
  • B
    Of strong gravity effect on TV signals
  • ✓
    TV signals travel straight and cannot follow the curvature of the earth
  • D
     There is atmosphere around the earth
Answer
Correct option: C.
TV signals travel straight and cannot follow the curvature of the earth
TV signals travel straight and cannot follow the curvature of the earth
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MCQ 1241 Mark
The ozone layer absorbs
  • A
     Infrared radiations
  • ✓
     Ultraviolet radiations
  • C
     X-rays
  • D
     g-rays
Answer
Correct option: B.
 Ultraviolet radiations
Ultraviolet radiations
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MCQ 1251 Mark
The electromagnetic waves travel with a velocity
  • A
    Equal to velocity of sound
  • ✓
     Equal to velocity of light
  • C
     Less than velocity of light
  • D
     None of these
Answer
Correct option: B.
 Equal to velocity of light
Equal to velocity of light
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MCQ 1261 Mark
Ozone is found in
  • ✓
     Stratosphere
  • B
    Ionosphere
  • C
    Mesosphere
  • D
    Troposphere
Answer
Correct option: A.
 Stratosphere
 Stratosphere
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MCQ 1271 Mark
In case of linearly polarized light, the magnitude of the electric field vector :
  • A
    Does not change with time
  • ✓
    Varies periodically with time
  • C
    Increases and decreases linearly with time
  • D
    Is parallel to the direction of propagation
Answer
Correct option: B.
Varies periodically with time
Varies periodically with time
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MCQ 1281 Mark
Which of the following are not electromagnetic waves
  • A
    Cosmic rays
  • B
    Gamma rays
  • ✓
    b-rays
  • D
     X-rays
Answer
Correct option: C.
b-rays
b-rays
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MCQ 1291 Mark
Which of the following radiations has the least wavelength
  • ✓
     g -rays
  • B
    b-rays
  • C
     a-rays
  • D
    X-rays
Answer
Correct option: A.
 g -rays
g -rays
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MCQ 1301 Mark
The speed of electromagnetic wave in vacuum depends upon the source of radiation
  • A
    Increases as we move from g-rays to radio waves
  • B
    Decreases as we move from g-rays to radio waves
  • ✓
    Is same for all of them
  • D
     None of these
Answer
Correct option: C.
Is same for all of them
 Is same for all of them
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MCQ 1311 Mark
The wavelength of light visible to eye is of the order of
  • A
    $10^{-2} m$
  • B
    $10^{-10} m$
  • C
    $1\  m$
  • ✓
    $6 \times 10^{-7 }\ m$
Answer
Correct option: D.
$6 \times 10^{-7 }\ m$
$6 \times 10^{-7 }\ m$
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MCQ 1321 Mark
Which of the following represents an infrared wavelength
  • ✓
    $10^{-4} cm$
  • B
    $10^{-5} cm$
  • C
    $10^{-6} cm$
  • D
    $10^{-7} cm$
Answer
Correct option: A.
$10^{-4} cm$
$10^{-4} cm$
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MCQ 1331 Mark
Which radiation in sunlight, causes heating effect
  • A
     Ultraviolet
  • ✓
     Infrared
  • C
    Visible light
  • D
     All of these
Answer
Correct option: B.
 Infrared
Infrared
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MCQ 1341 Mark
The range of wavelength of the visible light is
  • A
    10 Å to 100 Å
  • ✓
    4,000 Å to 8,000 Å
  • C
    8,000 Å to 10,000 Å
  • D
    10,000 Å to 15,000 Å
Answer
Correct option: B.
4,000 Å to 8,000 Å
4,000 Å to 8,000 Å
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MCQ 1351 Mark
Light is an electromagnetic wave. Its speed in vacuum is given by the expression
  • A
     $\sqrt{\mu_0 \varepsilon_0}$
  • B
    $\sqrt{\frac{\mu_0}{\varepsilon_0}}$
  • C
     $\sqrt{\frac{\varepsilon_0}{\mu_0}}$
  • ✓
     $\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$
Answer
Correct option: D.
 $\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$
 $\frac{1}{\sqrt{\mu_0 \varepsilon_0}}$
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MCQ 1361 Mark
Wave which cannot travel in vacuum is
  • A
     X-rays
  • ✓
     Infrasonic
  • C
    Ultraviolet
  • D
    Radiowaves
Answer
Correct option: B.
 Infrasonic
Infrasonic
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MCQ 1371 Mark
Pick out the longest wavelength from the following types of radiations
  • A
    Blue light
  • B
    g-rays
  • C
    X-rays
  • ✓
    Red light
Answer
Correct option: D.
Red light
 Red light
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MCQ 1381 Mark
Which of the following statement is wrong
  • ✓
     Infrared photon has more energy than the photon of visible light
  • B
     Photographic plates are sensitive to ultraviolet rays
  • C
     Photographic plates can be made sensitive to infrared rays
  • D
     Infrared rays are invisible but can cast shadows like visible light rays
Answer
Correct option: A.
 Infrared photon has more energy than the photon of visible light
Infrared photon has more energy than the photon of visible light
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MCQ 1391 Mark
For the study of the helical structure of nucleic acids, the property of electromagnetic radiation generally used is
  • A
     Reflection
  • B
    Interference
  • C
    Diffraction
  • ✓
    Polarization
Answer
Correct option: D.
Polarization
Polarization
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MCQ 1401 Mark
When the angle of incidence on a material is $60^{\circ}$, the reflected light is completely polarized. The velocity of the refracted ray inside the material is (in $\mathrm{ms}^{-1}$) 
  • A
    $3 \times 10^8$
  • B
    $\left(\frac{3}{\sqrt{2}}\right) \times 10^8$
  • ✓
    $\sqrt{3} \times 10^8$
  • D
    $0.5 \times 10^8$
Answer
Correct option: C.
$\sqrt{3} \times 10^8$
$\sqrt{3} \times 10^8$
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MCQ 1411 Mark
If a source is transmitting electromagnetic wave of frequency $8.2\times 10^6$  Hz, then wavelength of the electromagnetic waves transmitted from the source will be
  • ✓
    36.6 m
  • B
    40.5 m
  • C
    42.3 m
  • D
    50.9 m
Answer
Correct option: A.
36.6 m
(a) 36.6 m
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MCQ 1421 Mark
Heat radiations propagate with the speed of
  • A
    a-rays
  • B
     b-rays
  • ✓
     Light waves
  • D
    Sound waves
Answer
Correct option: C.
 Light waves
Light waves
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MCQ 1431 Mark
Energy stored in electromagnetic oscillations is in the form of
  • A
    Electrical energy
  • B
     Magnetic energy
  • ✓
     Both (a) and (b)
  • D
     None of these
Answer
Correct option: C.
 Both (a) and (b)
Both (a) and (b)
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MCQ 1441 Mark
Radio waves and visible light in vacuum have
  • ✓
     Same velocity but different wavelength
  • B
     Continuous emission spectrum
  • C
     Band absorption spectrum
  • D
     Line emission spectrum
Answer
Correct option: A.
 Same velocity but different wavelength
Same velocity but different wavelength
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MCQ 1451 Mark
The frequencies of X-rays, g-rays and ultraviolet rays are respectively a, b and c. Then
  • ✓
    a < b, b > c
  • B
     a > b, b > c
  • C
    a > b, b < c
  • D
    a < b, b < c
Answer
Correct option: A.
a < b, b > c
a < b, b > c
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MCQ 1461 Mark
Radio wave diffract around building although light waves do not. The reason is that radio waves
  • A
    Travel with speed larger than c
  • ✓
    Have much larger wavelength than light
  • C
    Carry news
  • D
     Are not electromagnetic waves
Answer
Correct option: B.
Have much larger wavelength than light
Have much larger wavelength than light
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MCQ 1471 Mark
Which rays are not the portion of electromagnetic spectrum
  • A
     X-rays
  • B
     Microwaves
  • ✓
    a-rays
  • D
    Radio waves
Answer
Correct option: C.
a-rays
a-rays
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MCQ 1481 Mark
What is ozone hole
  • A
     Hole in the ozone layer
  • B
    Formation of ozone layer
  • C
    Thinning of ozone layer in troposphere
  • ✓
     Reduction in ozone thickness in stratosphere
Answer
Correct option: D.
 Reduction in ozone thickness in stratosphere
 Reduction in ozone thickness in stratosphere
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MCQ 1491 Mark
Biological importance of Ozone layer is
  • ✓
    It stops ultraviolet rays
  • B
    Ozone rays reduce green house effect
  • C
    Ozone layer reflects radio waves
  • D
    Ozone layer controls $\mathrm{O}_2 / \mathrm{H}_2$ radio in atmosphere
Answer
Correct option: A.
It stops ultraviolet rays
(a) It stops ultraviolet rays
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MCQ 1501 Mark
In the propagation of electromagnetic waves the angle between the direction of propagation and plane of polarisation is
  • ✓
    $ 0^{\circ} $
  • B
    $ 45^{\circ} $
  • C
    $ 90^{\circ} $
  • D
    $ 180^{\circ}$
Answer
Correct option: A.
$ 0^{\circ} $
$0^{\circ}$
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M.C.Q (1 Marks) - Page 3 - Physics STD 12 Science Questions - Vidyadip