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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
If you are moving at relativistic speed between two points that are a fixed distance apart, then the distance between the two points appers
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larger
shorter
equal
none of these
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Question # 2
A particle having mass and charge equal to that of an electron is called:
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Proton
Positron
Pion
Pi-meson
Both (C) and (D)
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Question # 3
Which one of the following physical quantities changes with relativistic speed
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Length
Mass
Time
All of the above
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Question # 4
the dilation of time applies to the timing processes which are:
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Physical
Chemical
Biological
All of these
None of these
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Question # 5
According to Einstein, with the great increase in the speed of the body, the relativistic mass of the body
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Remains constant
Decreases
Increases to infinity
Reduced to zero
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Question # 6
When the atomic particle are moving with velocities approaching that of light:
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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 # 7
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 # 8
If A represents linear momentum and c, the velocity of light, then unit of pc in international system of units is:
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Newton
Joule
Joule-Sec
Joule-s
-1
Watt
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Question # 9
The photoelectric effect, the maximum energy of photoelectrons depends on the
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particular metal surface
frequency of incident light
both of them
none of them
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Question # 10
The special theory of relatively treats the problems involving:
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Inertial frames of reference
Non-inertial frames
Non-accelerated frame
Botha (A) and (C)
Both (B) and (C)
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Question # 11
When monochromatic light is allowed to fall on cathode, it begins to emit electrons, these electrons are called
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thermoionic electrons
free electrons
photoelectrons
slow electrons
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Question # 12
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 # 13
The energy of a photon is represented by
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h/c
2
h/T
hc
2
hf/c
2
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Question # 14
In order to produce pair production, a photon must have a energy
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0.511 Me v
0.256 Me v
1.02 Me v
0.956 Me v
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Question # 15
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
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1.66 m
1.0 m
0.66 m
2.66 m
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Question # 16
A black body is
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an ideal absorber
an ideal radiator
both of them
none of them
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