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

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ECAT Pre General Science Physics Chapter 19 Dawn of Modern Physics

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Question # 1

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

Question # 2

The photon of radio-waves has energy of about

Question # 3

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

Question # 4

The special theory of relativity is based on:

Question # 5

The special theory of relatively treats the problems involving:

Question # 6

In photoelectric effect the energy of ejected electrons depend on

Question # 7

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

Question # 8

When a position comes close to an electron they annihilate into

Question # 9

An inertial frame is that frame in which

Question # 10

When a platinum wire is heated, it appears yellow at

Question # 11

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

Question # 12

Due to relative motion of observer and the frame of reference of events, time always:

Question # 13

The way through which electromagnetic radiations or photons interact with matter depends upon their:

Question # 14

When the atomic particle are moving with velocities approaching that of light:

Question # 15

The concept of direction is purely:

Question # 16

The Einstein's changes in length, mass and time are not observed in common life because

Question # 17

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

Question # 18

The idea of quantization of energy was proposed by:

Question # 19

The energy of a photon in a beam of infrared radiation of wavelength 1240 nm is

Question # 20

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

Question # 21

Momentum is a parameter associated with

Question # 22

Photocell is a device which converts

Question # 23

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

Question # 24

The inside cavity of the black body is

Question # 25

the symbol to be used in relativity problems denotes:

Question # 26

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

Question # 27

The energy of photon 'E' is proported to

Question # 28

Max plank founded a mathematical model resulting in an equation that describes the shape of observed black body radiation curves exactly, in

Question # 29

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

Question # 30

Practically the quantity v/c is always:

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Sr.# Question Answer
1 The photoelectric effect, the maximum energy of photoelectrons depends on the
A. particular metal surface
B. frequency of incident light
C. both of them
D. none of them
2 There is no way to detect:
A. Absolute uniform motion
B. Accelerated motion
C. State rest
D. State of motion
3 According to the electromagnetic wave theory of light, increasing the intensity of incident light should increase the
A. number of photoelectrons
B. size of the photoelectrons
C. charge on photoelectrons
D. K.E of photoelectrons
4 If A represents linear momentum and c, the velocity of light, then unit of pc in international system of units is:
A. Newton
B. Joule
C. Joule-Sec
D. Joule-s-1
5 Photocell is a device which converts
A. chemical energy into electrical energy
B. electrical energy into light energy
C. heat energy into electrical energy
D. light energy into electrical energy
6 The mass 'm' of a body moving at 0.8 c (whose rest mass is mo) becomes
A. 2 mo
B. 1.67 mo
C. 0.67 mo
D. 2.67 mo
7 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
A. 1.66 m
B. 1.0 m
C. 0.66 m
D. 2.66 m
8 Albert Einstein got the Nobel prize in physics for his explanation of photoelectric effect in
A. 1916
B. 1919
C. 1921
D. 1923
9 Victor de-Brogile received the Nobel prize in physics in
A. 1925
B. 1929
C. 1932
D. 1935
10 If you are moving at relativistic speed between two points that are a fixed distance apart, then the distance between the two points appers
A. larger
B. shorter
C. equal
D. none of these
11 the symbol to be used in relativity problems denotes:
A. Dilated time
B. Proper time
C. Life time
D. Half time
12 Compton shift refers to:
A. Photon
B. Meson
C. Proton
D. Positron
13 The analysis of the distribution of wavelengths of the radiation emitted from a hot body set the foundation of new mechanics, known as
A. classical mechanics
B. Newtonian mechanics
C. quantum mechanics
D. statistical mechanics
14 If a material object moves with the speed of light 'C' its mass becomes
A. Equal to its rest mass
B. Four times of its rest mass
C. Double of its rest mass
D. Infinite
15 The special theory of relativity is based on:
A. Four postulates
B. Three postulates
C. Two postulates
D. One postulate
16 Davision and Germer performed experiment to verify
A. de-Brogile hypothesis
B. theory of relativity
C. Newton's law of gravitation
D. Mass-energy relation
17 A high temperature, the proportion of shorter wavelengths radiation, emitted by the body
A. decreases
B. first increases then decreases
C. increases
D. any one of them
18 The energy of photon 'E' is proported to
A. The magnetic field H
B. The electric field E
C. Both the electric and magnetic field H and E
D. Frequency
19 When a position comes close to an electron they annihilate into
A. one photon
B. two photons which travel in the same direction
C. two photons which travels in the opposite direction
D. two photons which travel in any direction
20 Compton studied the scattering of x-rays by loosely bound electrons from:
A. NaCl crystal
B. Graphite crystal
C. Zirconia
D. Copper crystal
21 Practically the quantity v/c is always:
A. less than one
B. Equal to one
C. Greater then one
D. all of these
22 A particle having mass and charge equal to that of an electron is called:
A. Proton
B. Positron
C. Pion
D. Pi-meson
23 Which one of the following physical quantities changes with relativistic speed
A. Length
B. Mass
C. Time
D. All of the above
24 Photoelectric effect takes place with a photon of:
A. Very high energy
B. Very low energy
C. Low energy
D. High energy
25 The year when A.H. compton was awarded Nobel Prize is:
A. 1923
B. 1927
C. 1931
D. 1935
26 The concept of direction and position are purely
A. absolute
B. relative
C. absolute or relative
D. none of these
27 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
28 The photon of radio-waves has energy of about
A. 1 Me V
B. 1 Ke v
C. 10-10e v
D. 1010e v
29 The nature of radiations emitted by a hot body depends upon its:
A. Metarial
B. Temperature
C. colour
D. Volume
30 Max plank founded a mathematical model resulting in an equation that describes the shape of observed black body radiation curves exactly, in
A. 1890
B. 1895
C. 1900
D. 1905

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