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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
Which of the following is not an example of intertial frame
Choose an answer
a body placed on the surface of earth
a body placed in a car moving with uniform velocity
a body placed in a car moving with same acceleration
none of these
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Question # 2
According to the Max plank, energy is redialed or absorbed in
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discrete packets
continuous waves
either of them
none of these
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Question # 3
The energy of a photon in a beam of infrared radiation of wavelength 1240 nm is
Choose an answer
100 ev
10
6
e v
10
3
e v
1.0 e v
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Question # 4
The intensity of emitted energy (with wavelength) radiated from a black body at different temperatures was initially measured by:
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Lummer
Planck
Pringsheim
Both (A ) and (B)
Both (A) and (C)
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Question # 5
The value of the Stephen's constant for black body radiations is given by
Choose an answer
5.6 x 10
8
Wm
-2
K
-4
5.67 x 10
-8
Wm
-2
K
-4
2.9 x 10
-3
mK
2.9 x 10
3
mK
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Question # 6
The value of threshold frequency for different metals is
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different
same
may be different or may be same
none of these
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Question # 7
Position was discovered by Carl Anderson in
Choose an answer
1920
1925
1928
1932
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Question # 8
The whole shape of the black body spectrum for all wavelengths was explained by the formula proposed by
Choose an answer
Max plank
Newton
Einstein
J.J. Thomson
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Question # 9
Max plank received the Nobel Prize in physics for his discovery of energy quanta in
Choose an answer
1900
1906
1912
1918
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Question # 10
Davision and Germer performed experiment to verify
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de-Brogile hypothesis
theory of relativity
Newton's law of gravitation
Mass-energy relation
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Question # 11
When monochromatic light is allowed to fall on cathode, it begins to emit electrons, these electrons are called
Choose an answer
thermoionic electrons
free electrons
photoelectrons
slow electrons
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Question # 12
When a position comes close to an electron they annihilate into photons such that
Choose an answer
each photon has energy 0.51 Me v
each photon has energy 1.02 Me v
each photon has energy 0.25 Me v
none of these
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Question # 13
The Stephen-Boltzmann law for the black body radiation is given by
Choose an answer
E = T
2
E = -T
2
E = T
4
E = -T
4
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Question # 14
The inside cavity of the black body is
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painted white
painted silver
blackened with soot
painted red
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Question # 15
Intensity of light determines the:
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Energy of each photon
Number of photons
Speed of photons
Size of photons
None of these
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Question # 16
If a material object moves with the speed of light 'C' its mass becomes
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Equal to its rest mass
Four times of its rest mass
Double of its rest mass
Infinite
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