ECAT Pre Computer Science Chapter 19 MCQ Test With Answer

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

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ECAT Physics Chapter 19 Dawn of Modern Physics

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Question # 1

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

Question # 2

Which of the following is not an example of intertial frame

Question # 3

The existence of position was predicted by Dirace in

Question # 4

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

Question # 5

At the temperature, a body emits radiation which is principally

Question # 6

The energy of the 4th orbit in hydrogen atom is

Question # 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

Question # 8

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

Question # 9

Absolute motion cannot be detected

Question # 10

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

Question # 11

The mass 'm' of a body moving at 0.8 c (whose rest mass is mo) becomes

Question # 12

When a platinum wire is heated, it appears white at

Question # 13

G.P. Thomson observer experimentally that electrons and neutrons possess

Question # 14

There is no way to detect:

Question # 15

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

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ECAT Physics Chapter 19 Important MCQ's

Sr.# Question Answer
1 The Stephen-Boltzmann law for the black body radiation is given by
A. E = T2
B. E = -T2
C. E = T4
D. E = -T4
2 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)
3 A black body is
A. an ideal absorber
B. an ideal radiator
C. both of them
D. none of them
4 The inside cavity of the black body is
A. painted white
B. painted silver
C. blackened with soot
D. painted red
5 The special theory of relativity is based on the
A. one postulate
B. two postulates
C. three postulates
D. four postulates
6 The threshold frequency of sodium is 6 x 106MHz. The cut-off wavelength for this metal will be
A. 500 m
B. 500 nm
C. 500 km
D. 500 cm
7 When a position comes close to an electron they annihilate into photons such that
A. each photon has energy 0.51 Me v
B. each photon has energy 1.02 Me v
C. each photon has energy 0.25 Me v
D. none of these
8 Max plank received the Nobel Prize in physics for his discovery of energy quanta in
A. 1900
B. 1906
C. 1912
D. 1918
9 In the compton's effect, it is found that the wavelength of incident x-rays is
A. greater than the wavelength of scattered x-rays
B. equal to the wavelength of scattered x-rays
C. less than the wavelength of scattered x-rays
D. any one of these
10 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

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