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ECAT Physics Chapter 19 Dawn of Modern Physics Online Test MCQs With Answers
Question # 1
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 # 2
According to the special theory of relativity, time is
Choose an answer
absolute quantity
not absolute quantity
constant quantity
none of these
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Question # 3
The nature of radiations emitted by a hot body depends upon its:
Choose an answer
Metarial
Temperature
colour
Volume
Length
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Question # 4
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 # 5
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 # 6
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 # 7
Photoelectric effect takes place with a photon of:
Choose an answer
Very high energy
Very low energy
Low energy
High energy
None of these
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Question # 8
If you are moving at relativistic speed between two points that are a fixed distance apart, then the distance between the two points appers
Choose an answer
larger
shorter
equal
none of these
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Question # 9
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 # 10
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 # 11
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 # 12
The threshold frequency of sodium is 6 x 10
6
MHz. The cut-off wavelength for this metal will be
Choose an answer
500 m
500 nm
500 km
500 cm
None of these
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Question # 13
Max plank founded a mathematical model resulting in an equation that describes the shape of observed black body radiation curves exactly, in
Choose an answer
1890
1895
1900
1905
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Question # 14
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 # 15
According to the Max plank, energy is redialed or absorbed in
Choose an answer
discrete packets
continuous waves
either of them
none of these
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