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

Question # 1

When a platinum wire is heated, it appears white at

1600°C A
900°C B
1100°C C
1300°C D

Question # 2

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 # 3

The inside cavity of the black body is

painted white A
painted silver B
blackened with soot C
painted red D

Question # 4

The length contraction happens only

Opposite to the direction of motion A
along the direction of motion B
perpendicular to the direction of motion C
In any direction D

Question # 5

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 # 6

A particle having mass and charge equal to that of an electron is called:

Proton A
Positron B
Pion C
Pi-meson D
Both (C) and (D) E

Question # 7

In order to produce pair production, a photon must have a energy

0.511 Me v A
0.256 Me v B
1.02 Me v C
0.956 Me v D

Question # 8

When a platinum wire is heated, it appears orange red at

500°C A
900°C B
1100°C C
1300°C D

Question # 9

Compton was awarded Nobel prize in physics in

1921 A
1923 B
1925 C
1927 D

Question # 10

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 # 11

the symbol to be used in relativity problems denotes:

Dilated time A
Proper time B
Life time C
Half time D
None of these E

Question # 12

Electromagnetic -radiation means:

Photons A
protons B
Electrons C
Mesons D
None of these E

Question # 13

0.1 kg mass will be equivalent to the energy

9 x 10¹⁵J A
5 x 10⁸J B
6 x 10¹⁶J C
9 x 10^-16J D

Question # 14

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

Question # 15

Wien's constant is measured in:

Metre per kelviin A
Metre kelvin B
Kelvin per meter C
Joules D
Dynes E

Question # 16

The speed of a pendulum is measured to be 3.0 s in the inertial reference frame of the pendulum. What is its period measured by an observer moving at a speed of 0.95 c with respect to the pendulum

2.9 s A
3.0 s B
6.6 s C
9.6 s D

Question # 17

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

1.66 m A
1.0 m B
0.66 m C
2.66 m D

Question # 18

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 # 19

When a high energy photon interact with a metal, which of the following effect is most likely to be taken place

pair production A
photoelectric effect B
Compton effect C
None of these D

Question # 20

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 # 21

The analysis of the distribution of wavelengths of the radiation emitted from a hot body set the foundation of new mechanics, known as

classical mechanics A
Newtonian mechanics B
quantum mechanics C
statistical mechanics D

Question # 22

If a material object moves with the speed of light 'C' its mass becomes

Equal to its rest mass A
Four times of its rest mass B
Double of its rest mass C
Infinite D

Question # 23

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 # 24

According to the special theory of relativity, time is

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

Question # 25

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 # 26

The energy of a photon is represented by

h/c² A
h/T B
hc² C
hf/c² D

Question # 27

An electron is accelerated through a potential difference of 50v. its de-Brogile wavelength is

1.66 x 10^-29m A
1.74 x 10^-10cm B
17.4 x 10^-6m C
1.74 x 10^-10m D

Question # 28

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 # 29

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 # 30

A photon is considered to have

Momentum A
Energy B
Wavelength C
All of the above D

Sr.#	Question	Answer
1	Compton shift refers to:	A. Photon B. Meson C. Proton D. Positron
2	The length contraction happens only	A. Opposite to the direction of motion B. along the direction of motion C. perpendicular to the direction of motion D. In any direction
3	Due to relative motion of observer and the frame of reference of events, time always:	A. Dilates itself B. Contracts itself C. Stretches itself D. Both (A) and (C)
4	Converse of pair production is known as	A. Compton effect B. annihilation of matter C. photoelectric effect D. none of these
5	In photoelectric effect the energy of ejected electrons depend on	A. The frequency B. The intensity C. Both frequency and intensity D. None of these
6	The location and speed anywhere on earth can now be determined using relativistic effects by NAVISTAR to an accuracy of	A. 2 cm/s B. 20 cm/s C. 200 cm/s D. 2000 cm/s
7	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)
8	The inside cavity of the black body is	A. painted white B. painted silver C. blackened with soot D. painted red
9	As the light shines on the metal surface, the electrons are ejected	A. slowly B. instantaneously C. either of these D. none of these
10	There is certain frequency below which no electrons are emitted from the metal surface, this frequency is known as	A. maximum frequency B. minimum frequency C. threshold frequency D. all of these

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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