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ECAT Pre General Science Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
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 # 2
According to Einstein, with the great increase in the speed of the body the relativistic length of the body
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Remains constant
Decreases
Increases
Reduces to zero
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Question # 3
The ratio of energy E to the corresponding frequency (f) of the radiation (emitted or absorbed) is called:
Choose an answer
Wien's constant
Stefen's constnat
Planck's constant
Boltzmann's constant
None of these
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Question # 4
Strictly speaking, the earth is:
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An accelerated frame of reference
A non-inertial frame of reference
An inertial frame of reference
A non-accelerated frame of reference
Both (A) and (B)
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Question # 5
The emission of electrons from a metal surface when exposed to light of suitable frequency is called the
Choose an answer
pair production
Compton effect
photoelectric effect
relativity
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Question # 6
When a platinum wire is heated, it appears yellow at
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1600°C
900°C
1100°C
1300°C
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Question # 7
The energy of the 4th orbit in hydrogen atom is
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2.5 ev
- 3.5 ev
-0.85 ev
-13.6 ev
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Question # 8
Electromagnetic radiation or photons interact with matter in
Choose an answer
two distinct ways
three distinct ways
four distinct ways
five distinct ways
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Question # 9
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 # 10
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 # 11
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 # 12
If a body reaches a speed equal to the speed of light, then its mass will became
Choose an answer
zero
very small
infinity
none of these
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Question # 13
The length contraction happens only
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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 # 14
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 # 15
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 # 16
The stopping voltage for a certain metal is 100 volts, then the work function for the cathode plate is
Choose an answer
100 J
1.6 x 10
-17
J
100 eV
1.6 x 10
-17
eV
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Question # 17
Current, voltage, resistance measuring circuit is connected with the galvanometer with the help of switch, known as
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ON switch
off switch
function switch
none of these
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Question # 18
Absolute motion cannot be detected
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in its own frame of references
in a different frame of references
both in its frame and different frame of references
none of these
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Question # 19
Max plank founded a mathematical model resulting in an equation that describes the shape of observed black body radiation curves exactly, in
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1890
1895
1900
1905
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Question # 20
According to the de-Brogile relation, an object of large mass and ordinary speed has
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very small wavelength
very large wavelength
very small frequency
all of these
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Question # 21
An intertial frame of reference is a frame of reference which is
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at rest
moving with uniform velocity
either at rest or moving with uniform velocity
none of these
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Question # 22
According to the special theory of relativity
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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 # 23
The mass 'm' of a body moving at 0.8 c (whose rest mass is mo) becomes
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2 mo
1.67 mo
0.67 mo
2.67 mo
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Question # 24
Practically the quantity v/c is always:
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less than one
Equal to one
Greater then one
all of these
None of these
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Question # 25
the symbol to be used in relativity problems denotes:
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Dilated time
Proper time
Life time
Half time
None of these
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Question # 26
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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Question # 27
The Einstein's changes in length, mass and time are not observed in common life because
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We dont observer then seriously
The masses are too large
Their speed is too small than the speed of right
All of the above
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Question # 28
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 # 29
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 # 30
G.P. Thomson observer experimentally that electrons and neutrons possess
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particle-like properties
wave-like properties
neither particle nor wave like properties
none of these
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Question # 31
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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