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

Question # 1

In the compton's effect, it is found that the wavelength of incident x-rays is

greater than the wavelength of scattered x-rays A
equal to the wavelength of scattered x-rays B
less than the wavelength of scattered x-rays C
any one of these D

Question # 2

According to Einstein, with the great increase in the speed of the body the relativistic length of the body

Remains constant A
Decreases B
Increases C
Reduces to zero D

Question # 3

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 # 4

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 # 5

Practically the quantity v/c is always:

less than one A
Equal to one B
Greater then one C
all of these D
None of these E

Question # 6

According to the electromagnetic wave theory of light, increasing the intensity of incident light should increase the

number of photoelectrons A
size of the photoelectrons B
charge on photoelectrons C
K.E of photoelectrons D

Question # 7

Converse of pair production is known as

Compton effect A
annihilation of matter B
photoelectric effect C
none of these D

Question # 8

Max plank received the Nobel Prize in physics for his discovery of energy quanta in

1900 A
1906 B
1912 C
1918 D

Question # 9

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 # 10

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 # 11

The year when A.H. compton was awarded Nobel Prize is:

1923 A
1927 B
1931 C
1935 D
None of these E

Question # 12

The ratio of energy E to the corresponding frequency (f) of the radiation (emitted or absorbed) is called:

Wien's constant A
Stefen's constnat B
Planck's constant C
Boltzmann's constant D
None of these E

Question # 13

According to Einstein, with the great increase in the speed of the body, the relativistic mass of the body

Remains constant A
Decreases B
Increases to infinity C
Reduced to zero D

Question # 14

When a platinum wire is heated, it appears white at

1600°C A
900°C B
1100°C C
1300°C D

Question # 15

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 # 16

According to the special theory of relativity, time is

absolute quantity A
not absolute quantity B
constant quantity C
none of these D

Question # 17

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 # 18

Which of the following is not an example of intertial frame

a body placed on the surface of earth A
a body placed in a car moving with uniform velocity B
a body placed in a car moving with same acceleration C
none of these D

Question # 19

At the temperature, a body emits radiation which is principally

of long wavelengths in the visible region A
of long wavelengths in the invisible infrared region B
of short wavelength in invisible ultraviolet region C
none of these D

Question # 20

A black body is

an ideal absorber A
an ideal radiator B
both of them C
none of them D

Question # 21

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 # 22

Strictly speaking, the earth is:

An accelerated frame of reference A
A non-inertial frame of reference B
An inertial frame of reference C
^{A non-accelerated frame of reference} D
Both (A) and (B) E

Question # 23

The concept of direction and position are purely

absolute A
relative B
absolute or relative C
none of these D

Question # 24

When a platinum wire is heated, it appears yellow at

1600°C A
900°C B
1100°C C
1300°C D

Question # 25

Compton was awarded Nobel prize in physics in

1921 A
1923 B
1925 C
1927 D

Question # 26

Electromagnetic radiation or photons interact with matter in

two distinct ways A
three distinct ways B
four distinct ways C
five distinct ways D

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

According to the special theory of relativity, a moving clock

runs faster A
runs slower B
neither runs faster nor slower C
all of these D

Question # 29

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 # 30

The special theory of relativity treats problems invoving

inertial frame of references A
accelerating frame of references B
both of these C
none of these D

Sr.#	Question	Answer
1	A non-inertial frame of reference is one, in which	A. law of inertial is valid B. all laws of physics are the same in all frames C. a>0 or a<0 D. a=0
2	The existence of position was predicted by Dirace in	A. 1920 B. 1925 C. 1930 D. 1928
3	When a platinum wire is heated, it appears dull red at about	A. 500°C B. 900°C C. 1100°C D. 1300°C
4	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
5	There is no way to detect:	A. Absolute uniform motion B. Accelerated motion C. State rest D. State of motion
6	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
7	Intensity of light determines the:	A. Energy of each photon B. Number of photons C. Speed of photons D. Size of photons
8	The ratio of energy E to the corresponding frequency (f) of the radiation (emitted or absorbed) is called:	A. Wien's constant B. Stefen's constnat C. Planck's constant D. Boltzmann's constant
9	According to the special theory of relativity	A. mass and energy are same entities B. mass and energy are same entities but interconverible C. mass and energy are different entities but interconverible D. mass and energy are different entities but non-interconveritble
10	The special theory of relativity is based on the	A. one postulate B. two postulates C. three postulates D. four postulates

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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