ECAT Pre Computer Science Chapter 19 MCQ Test With Answer

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

Try The 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

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

Question # 2

Compton shift refers to:

Question # 3

According to the special theory of relativity

Question # 4

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

Question # 5

The existence of position was predicted by Dirace in

Question # 6

Which one of the following physical quantities changes with relativistic speed

Question # 7

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

Question # 8

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

Question # 9

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

Question # 10

Which of the following phenomenon proves the particle nature of light

Question # 11

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

Question # 12

Wave nature of particle was proposed by

Question # 13

According to the special theory of relativity, a moving clock

Question # 14

Wien's constant is measured in:

Question # 15

Position was discovered by Carl Anderson in

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ECAT Physics Chapter 19 Important MCQ's

Sr.# Question Answer
1 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)
2 If the radius of first orbit of hydrogen atom is 0.53° A the radius of second orbit will be
A. 2.120°A
B. 0.212°A
C. 21.2°A
D. 0.14°
a
3 The unit of work function is:
A. Joule
B. Electron volt
C. That of threshold frequency
D. Both (A) and (B)
4 From the theory of relativity, momentum p of the photon is related to energy as
A. p = hfc
B. p = hf/c
C. p = f(hc,f)
D. p = cf/h
5 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
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 According to Einstein, with the great increase in the speed of the body, the relativistic mass of the body
A. Remains constant
B. Decreases
C. Increases to infinity
D. Reduced to zero
8 The value of the Stephen's constant for black body radiations is given by
A. 5.6 x 108Wm-2K-4
B. 5.67 x 10-8Wm-2K-4
C. 2.9 x 10-3mK
D. 2.9 x 103mK
9 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
10 The photon of radio-waves has energy of about
A. 1 Me V
B. 1 Ke v
C. 10-10e v
D. 1010e v

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