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Online Tests
ECAT Pre General Science Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
Which one of the following physical quantities changes with relativistic speed
Choose an answer
Length
Mass
Time
All of the above
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Question # 2
The idea of quantization of energy was proposed by:
Choose an answer
Einstein
Max.Planck
Maxwell
Bohr
Rutherford
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Question # 3
The year when A.H. compton was awarded Nobel Prize is:
Choose an answer
1923
1927
1931
1935
None of these
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Question # 4
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 # 5
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 # 6
Max Planck received the Nobel Prize for his discovery of energy quants in:
Choose an answer
1718 AD
1918 AH
1818 AD
1918 AD
None of these
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Question # 7
If the radius of first orbit of hydrogen atom is 0.53
° A the radius of second orbit will be
Choose an answer
2.120
°A
0.212
°A
21.2
°A
0.14
°
a
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Question # 8
The energy of the 4th orbit in hydrogen atom is
Choose an answer
2.5 ev
- 3.5 ev
-0.85 ev
-13.6 ev
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Question # 9
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 # 10
Compton derived an expression to find compton shift by applying to the process, the law of conservation of:
Choose an answer
Energy only
Momentum only
Mass only
Charge only
Both (A) and (B)
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Question # 11
When the atomic particle are moving with velocities approaching that of light:
Choose an answer
Newton's laws become valid
Relativistic effects become prominent
Botha(A) and (B) are valid
Neither (A)nor (B)
There mass becomes zero.
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Question # 12
The length contraction happens only
Choose an answer
Opposite to the direction of motion
along the direction of motion
perpendicular to the direction of motion
In any direction
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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
Momentum is a parameter associated with
Choose an answer
wave motion
particle motion
neither wave nor particle motion
none of these
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Question # 15
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 # 16
As the light shines on the metal surface, the electrons are ejected
Choose an answer
slowly
instantaneously
either of these
none of these
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Question # 17
When platinum wire is heated, then at the temperature of 500
o
C, it becomes:
Choose an answer
Yellow
Orange red
Dull red
White
Cherry red
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Question # 18
The existence of position was predicted by Dirace in
Choose an answer
1920
1925
1930
1928
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Question # 19
The unit of work function is:
Choose an answer
Joule
Electron volt
That of threshold frequency
Both (A) and (B)
None of these
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Question # 20
When a platinum wire is heated, it appears yellow at
Choose an answer
1600°C
900°C
1100°C
1300°C
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Question # 21
When low energy photon interact with a metal,which of the following effect is likely to be taken place
Choose an answer
pair production
photoelectric
Compton effect
None of these
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Question # 22
There is no way to detect:
Choose an answer
Absolute uniform motion
Accelerated motion
State rest
State of motion
None of these
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Question # 23
According to the special theory of relativity
Choose an answer
mass and energy are same entities
mass and energy are same entities but interconverible
mass and energy are different entities but interconverible
mass and energy are different entities but non-interconveritble
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Question # 24
A bar 1.0 m in length and located along x-axix moves with a speed of 0.75 c with respect to a stationary observer. The length of the bar as measured by the stationary observer is
Choose an answer
1.66 m
1.0 m
0.66 m
2.66 m
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Question # 25
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 # 26
de-Broglies hypthesis was experimentally verified by
Choose an answer
Maxwell
Compton
Einstein
Davison and Germer
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Question # 27
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 # 28
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 # 29
According to the electromagnetic wave theory of light, increasing the intensity of incident light should increase the
Choose an answer
number of photoelectrons
size of the photoelectrons
charge on photoelectrons
K.E of photoelectrons
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Question # 30
The location and speed anywhere on earth can now be determined using relativistic effects by NAVISTAR to an accuracy of
Choose an answer
2 cm/s
20 cm/s
200 cm/s
2000 cm/s
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