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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
In photoelectric effect the energy of ejected electrons depend on
Choose an answer
The frequency
The intensity
Both frequency and intensity
None of these
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Question # 2
When platinum wire is heated, it appears cherry red at
Choose an answer
1600
°C
900
°C
1100
°C
1300
°C
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Question # 3
Albert Einstein got the Nobel prize in physics for his explanation of photoelectric effect in
Choose an answer
1916
1919
1921
1923
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Question # 4
The concept of direction is purely:
Choose an answer
Absolute
Relative
Relative to stars always
Relative to the sun always
None of these
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Question # 5
An electron is accelerated through a potential difference of 50v. its de-Brogile wavelength is
Choose an answer
1.66 x 10
-29
m
1.74 x 10
-10
cm
17.4 x 10
-6
m
1.74 x 10
-10
m
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Question # 6
The value of the plank's constant 'h' is given by
Choose an answer
1.6 x 10
-19
J
1.67 x 10
-27
Kg
6.63 x 10
34
Js
6.63 x 10
-34
Js
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Question # 7
Position and momentum of a particle cannot both be measured simultaneously with perfect accuracy. This is the statement of
Choose an answer
photoelectric effect
pair production
Compton effect
uncertainty principle
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Question # 8
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 # 9
The positron was discovered by:
Choose an answer
In cosmic radiation
In 1932
By Carl Anderson
All above
By direc
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Question # 10
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 # 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 photon of radio-waves has energy of about
Choose an answer
1 Me V
1 Ke v
10
-10
e v
10
10
e v
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Question # 13
Compton studied the scattering of x-rays by loosely bound electrons from:
Choose an answer
NaCl crystal
Graphite crystal
Zirconia
Copper crystal
None of these
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Question # 14
The intensity of emitted energy (with wavelength) radiated from a black body at different temperatures was initially measured by:
Choose an answer
Lummer
Planck
Pringsheim
Both (A ) and (B)
Both (A) and (C)
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Question # 15
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 # 16
The mass of an object will be doubled at speed
Choose an answer
1.6 x 10
8
ms
-1
2.6 X 10
8
ms
-1
2.6 x 10
7
ms
-1
2.6 x 10
9
ms
-1
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Question # 17
Victor de-Brogile received the Nobel prize in physics in
Choose an answer
1925
1929
1932
1935
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Question # 18
According to the de-Brogile relation, an object of large mass and ordinary speed has
Choose an answer
very small wavelength
very large wavelength
very small frequency
all of these
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Question # 19
The idea of quantization of energy was proposed by:
Choose an answer
Einstein
Max.Planck
Maxwell
Bohr
Rutherford
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