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

When a platinum wire is heated, it appears dull red at about

Question # 2

The emission of electrons from a metal surface when exposed to light of suitable frequency is called the

Question # 3

The photoelectric effect, the maximum energy of photoelectrons depends on the

Question # 4

The unit of work function is:

Question # 5

Electromagnetic radiation or photons interact with matter in

Question # 6

The stopping voltage for a certain metal is 100 volts, then the work function for the cathode plate is

Question # 7

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

Question # 8

According to the special theory of relativity

Question # 9

If a body reaches a speed equal to the speed of light, then its mass will became

Question # 10

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

Question # 11

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

Question # 12

S.I. unit of planks constant is

Question # 13

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

Question # 14

When platinum wire is heated, it appears cherry red at

Question # 15

Practically the quantity v/c is always:

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ECAT Physics Chapter 19 Important MCQ's

Sr.# Question Answer
1 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
2 The special theory of relativity is based on the
A. one postulate
B. two postulates
C. three postulates
D. four postulates
3 An electron is accelerated through a potential difference of 50v. its de-Brogile wavelength is
A. 1.66 x 10-29m
B. 1.74 x 10-10cm
C. 17.4 x 10-6m
D. 1.74 x 10-10m
4 Max Planck received the Nobel Prize for his discovery of energy quants in:
A. 1718 AD
B. 1918 AH
C. 1818 AD
D. 1918 AD
5 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
6 The energy of a photon in a beam of infrared radiation of wavelength 1240 nm is
A. 100 ev
B. 106e v
C. 103e v
D. 1.0 e v
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 The positron was discovered by:
A. In cosmic radiation
B. In 1932
C. By Carl Anderson
D. All above
9 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
10 When a platinum wire is heated, it appears white at
A. 1600°C
B. 900°C
C. 1100°C
D. 1300°C

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