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Physics ECAT Pre Engineering Chapter 19 Dawn of Modern Physics Physics Online Test MCQs With Answers
Question # 1
The special theory of relativity is based on:
Choose an answer
Four postulates
Three postulates
Two postulates
One postulate
None of these
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Question # 2
A black body is
Choose an answer
an ideal absorber
an ideal radiator
both of them
none of them
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Question # 3
When a position comes close to an electron they annihilate into
Choose an answer
one photon
two photons which travel in the same direction
two photons which travels in the opposite direction
two photons which travel in any direction
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Question # 4
Current, voltage, resistance measuring circuit is connected with the galvanometer with the help of switch, known as
Choose an answer
ON switch
off switch
function switch
none of these
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Question # 5
Intensity of light determines the:
Choose an answer
Energy of each photon
Number of photons
Speed of photons
Size of photons
None of these
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Question # 6
A photon is considered to have
Choose an answer
Momentum
Energy
Wavelength
All of the above
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Question # 7
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 # 8
A particle having mass and charge equal to that of an electron is called:
Choose an answer
Proton
Positron
Pion
Pi-meson
Both (C) and (D)
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Question # 9
According to the special theory of relativity, a moving clock
Choose an answer
runs faster
runs slower
neither runs faster nor slower
all of these
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Question # 10
According to Einstein, with the great increase in the speed of the body the relativistic length of the body
Choose an answer
Remains constant
Decreases
Increases
Reduces to zero
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Question # 11
G.P. Thomson observer experimentally that electrons and neutrons possess
Choose an answer
particle-like properties
wave-like properties
neither particle nor wave like properties
none of these
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Question # 12
The special theory of relativity is based on the
Choose an answer
one postulate
two postulates
three postulates
four postulates
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Question # 13
Compton shift refers to:
Choose an answer
Photon
Meson
Proton
Positron
Both (B) and (D)
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Question # 14
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 # 15
Due to relative motion of observer and the frame of reference of events, time always:
Choose an answer
Dilates itself
Contracts itself
Stretches itself
Both (A) and (C)
None of these
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Question # 16
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 # 17
Electromagnetic -radiation means:
Choose an answer
Photons
protons
Electrons
Mesons
None of these
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Question # 18
S.I. unit of planks constant is
Choose an answer
J-s
-1
J.s
J.s
-2
J.s
2
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Question # 19
A high temperature, the proportion of shorter wavelengths radiation, emitted by the body
Choose an answer
decreases
first increases then decreases
increases
any one of them
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