ECAT Pre General Science Chapter 19 online mcq test with answers for Physics chapter 19 (Dawn of Modern Physics)

Question # 1

A non-inertial frame of reference is one, in which

law of inertial is valid A
all laws of physics are the same in all frames B
a>0 or a<0 C
a=0 D

Question # 2

The mass of an object will be doubled at speed

1.6 x 10⁸ms^-1 A
2.6 X 10⁸ms^-1 B
2.6 x 10⁷ms^-1 C
2.6 x 10⁹ms^-1 D

Question # 3

The threshold frequency of sodium is 6 x 10⁶MHz. The cut-off wavelength for this metal will be

500 m A
500 nm B
500 km C
500 cm D
None of these E

Question # 4

The energy of the 4th orbit in hydrogen atom is

2.5 ev A
- 3.5 ev B
-0.85 ev C
-13.6 ev D

Question # 5

When a position comes close to an electron they annihilate into photons such that

each photon has energy 0.51 Me v A
each photon has energy 1.02 Me v B
each photon has energy 0.25 Me v C
none of these D

Question # 6

The Stephen-Boltzmann law for the black body radiation is given by

E = T² A
E = -T² B
E = T⁴ C
E = -T⁴ D

Question # 7

The whole shape of the black body spectrum for all wavelengths was explained by the formula proposed by

Max plank A
Newton B
Einstein C
J.J. Thomson D

Question # 8

When a platinum wire is heated, it appears yellow at

1600°C A
900°C B
1100°C C
1300°C D

Question # 9

Compton derived an expression to find compton shift by applying to the process, the law of conservation of:

Energy only A
Momentum only B
Mass only C
Charge only D
Both (A) and (B) E

Question # 10

Compton was awarded Nobel prize in physics in

1921 A
1923 B
1925 C
1927 D

Question # 11

The value of the plank's constant 'h' is given by

1.6 x 10^-19J A
1.67 x 10^-27Kg B
6.63 x 10³⁴Js C
6.63 x 10^-34Js D

Question # 12

The energy of a photon is represented by

h/c² A
h/T B
hc² C
hf/c² D

Question # 13

According to the de-Brogile relation, an object of large mass and ordinary speed has

very small wavelength A
very large wavelength B
very small frequency C
all of these D

Question # 14

There is certain frequency below which no electrons are emitted from the metal surface, this frequency is known as

maximum frequency A
minimum frequency B
threshold frequency C
all of these D

Question # 15

The special theory of relativity is based on:

Four postulates A
Three postulates B
Two postulates C
One postulate D
None of these E

Question # 16

If the radius of first orbit of hydrogen atom is 0.53° A the radius of second orbit will be

2.120°A A
0.212°A B
21.2°A C
0.14°
a
D

Question # 17

Which of the following phenomenon proves the particle nature of light

interference A
diffraction B
photoelectric effect C
none of these D

Question # 18

The concept of direction is purely:

Absolute A
Relative B
Relative to stars always C
Relative to the sun always D
None of these E

Question # 19

Position and momentum of a particle cannot both be measured simultaneously with perfect accuracy. This is the statement of

photoelectric effect A
pair production B
Compton effect C
uncertainty principle D

Question # 20

Photoelectrons are emitted when ultraviolet light falls on:

Casium A
Silver B
Potassium C
Any of these D
None of these E

Question # 21

A high temperature, the proportion of shorter wavelengths radiation, emitted by the body

decreases A
first increases then decreases B
increases C
any one of them D

Question # 22

According to the Max plank, energy is redialed or absorbed in

discrete packets A
continuous waves B
either of them C
none of these D

Question # 23

The positron was discovered by:

In cosmic radiation A
In 1932 B
By Carl Anderson C
All above D
By direc E

Question # 24

The intensity of emitted energy (with wavelength) radiated from a black body at different temperatures was initially measured by:

Lummer A
Planck B
Pringsheim C
Both (A ) and (B) D
Both (A) and (C) E

Question # 25

In process of annihilation of matter, the two photons produced move in opposite direction to converse

momentum A
charge B
energy C
mass D

Question # 26

the dilation of time applies to the timing processes which are:

Physical A
Chemical B
Biological C
All of these D
None of these E

Question # 27

Absolute motion cannot be detected

in its own frame of references A
in a different frame of references B
both in its frame and different frame of references C
none of these D

Question # 28

The value of the Stephen's constant for black body radiations is given by

5.6 x 10⁸Wm^-2K^-4 A
5.67 x 10^-8Wm^-2K^-4 B
2.9 x 10^-3mK C
2.9 x 10³mK D

Question # 29

In photoelectric effect the energy of ejected electrons depend on

The frequency A
The intensity B
Both frequency and intensity C
None of these D

Question # 30

An intertial frame of reference is a frame of reference which is

at rest A
moving with uniform velocity B
either at rest or moving with uniform velocity C
none of these D

Sr.#	Question	Answer
1	The intensity of emitted energy (with wavelength) radiated from a black body at different temperatures was initially measured by:	A. Lummer B. Planck C. Pringsheim D. Both (A ) and (B)
2	The whole shape of the black body spectrum for all wavelengths was explained by the formula proposed by	A. Max plank B. Newton C. Einstein D. J.J. Thomson
3	The value of threshold frequency for different metals is	A. different B. same C. may be different or may be same D. none of these
4	Albert Einstein got the Nobel prize in physics for his explanation of photoelectric effect in	A. 1916 B. 1919 C. 1921 D. 1923
5	According to Einstein, with the great increase in the speed of the body the relativistic length of the body	A. Remains constant B. Decreases C. Increases D. Reduces to zero
6	When the atomic particle are moving with velocities approaching that of light:	A. Newton's laws become valid B. Relativistic effects become prominent C. Botha(A) and (B) are valid D. Neither (A)nor (B)
7	If a body reaches a speed equal to the speed of light, then its mass will became	A. zero B. very small C. infinity D. none of these
8	A photon is considered to have	A. Momentum B. Energy C. Wavelength D. All of the above
9	The year when A.H. compton was awarded Nobel Prize is:	A. 1923 B. 1927 C. 1931 D. 1935
10	Compton derived an expression to find compton shift by applying to the process, the law of conservation of:	A. Energy only B. Momentum only C. Mass only D. Charge only

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ECAT Pre General Science Physics Chapter 19 MCQ Test With Answer

MCQ's Test For ECAT Pre General Science Physics Chapter 19 Dawn of Modern Physics

ECAT Pre General Science Physics Chapter 19 Dawn of Modern Physics