NCERT Solutions for class 12 Physics | Chapter 11 - Dual Nature of Radiation and Matter

Questions
1 In photo electric emission, for alkali metals the threshold frequency lies in the:
A visible region
B ultraviolet region
C infrared region
D far end of the infrared region

Answer:visible region
2 The charge of a photo electron is :
A 9.1 × 10-31 C
B 9.1 × 10-27 C
C 9.1 × 10-24 C
D none of these

Answer:none of these

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3 What is the de-Broglie wavelength of an electron accelerated from rest through a potential difference of V volts?
A Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
B Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
C Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
D None of these

Answer:A
4 X-rays are:
A deflected by an electric field
B deflected by a magnetic field
C deflected by both electric and magnetic fields
D not deflected by electric and magnetic fields

Answer:not deflected by electric and magnetic fields
5 The work function of photoelectric material is 3.3 eV. The threshold frequency will be equal to:
A 8 × 1014 Hz
B 8 × 1010 Hz
C 5 × 1010 Hz
D 4 × 1014 Hz

Answer:8 × 1014 Hz
6 The ratio of specific charge of an alpha particle to the proton is:
A 1 : 2
B 2 : 1
C 4 : 1
D 1 : 4

Answer:1 : 2
7 Protons and alpha particles have the same de-Broglie wavelength. What is same for both of them ?
A Energy
B Time period
C Frequency
D Momentum

Answer:Momentum
8 Millikan’s oil drop experiment makes use of:
A Stokes’ law
B Boyle’s law
C Gas equation
D Bernoulli’s theorem

Answer:Stokes’ law
9 The number of photons of frequency n present in energy E, in terms of Planck’s constant h:
A E/nh
B nhE
C nh/E
D nE/h

Answer:E/nh
10 Name the scientists who first studied the passage of electricity through fluids to establish the electrical nature of matter:
A Millikan
B Planck
C Faraday
D Boyle

Answer:Faraday
11 The different stages of discharge in a discharge tube can be explained on the basis of:
A the wave nature of light
B the dual nature of light
C wave nature of electrons
D the collision between the charged particles emitted from the cathode the atoms of the gas in the tube

Answer:the collision between the charged particles emitted from the cathode the atoms of the gas in the tube
12 The momentum of an electron that emits a wavelength of 2 Å. will be:
A 6.4 × 10-36 kgms-1
B 3.3 × 10-24 kgms-1
C 3.3 × 10-34 kgms-1

D none of these

Answer:3.3 × 10-24 kgms-1
13 In Thomson’s experiment number of parabola gives :
A the no. of electrons present in element
B the no. of proton present in element
C the no. of neutrons present in element
D the no. of isotopes of the element present

Answer:the no. of isotopes of the element present
14 De-Broglie equation states the:
A dual nature
B particle nature
C wave nature
D None of these

Answer:dual nature
15 The strength of photoelectric current depends upon :
A angle of incident radiation
B frequency of incident radiation
C intensity of incident radiation
D distance between anode and cathode

Answer:frequency of incident radiation
16 What is the de-Broglie wavelength of a proton accelerated from rest through a potential difference of V volts?
A Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
B Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
C Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
D None of these

Answer:None of these
17 In Davisson – Germer experiment, if the angle of diffraction is 52o, then the glancing angle will be:
A 32°
B 64°
C 72°
D 92°

Answer:64°
18 In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
A increasing the potential different between the anode and filament
B increasing the filament current
C decreasing the filament current
D decreasing the potential difference between the anode and filament

Answer:decreasing the potential difference between the anode and filament
19 The energy of photon is equal to the K.E. of a proton. The energy of the photon is E. Let λ1  be the de- Broglie wavelength of the proton and  be the wavelength of the photon. The ratio λ1/ λ2 is proportional to
A Eo
B E1/2
C E-1
D E-1/2

Answer:E1/2
20 The ratio of momenta of an electron and an alpha particle which are accelerated from rest through a potential different of 100 volt is
A 1:1
B Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
C Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter
D Class 12 Physics Chapter 11 Dual Nature of Radiation and Matter

Answer:D

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