Class 12 Dual Nature Of Radiation And Matter CBSE Questions & Answers

Class 12 · Dual Nature Of Radiation And Matter

This is Physics Class 12 Dual Nature Of Radiation and Matter CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Threshold wavelength for metal is 10,000 \(\mathop A\limits^0 \). If light of wavelength 5461 \(\mathop A\limits^0 \) is incident on it then stopping potential is 1.02 V, then value of Planck’s constant is
  • A
    6.67 \( \times {\rm{ 1}}{0^{ - {\rm{34}}}}\) J-secs
  • B
    6.45 \( \times {\rm{ 1}}{0^{ - {\rm{34}}}}\) J-secs
  • C
    6.60 \( \times {\rm{ 1}}{0^{ - {\rm{34}}}}\)J-secs
  • D
    6.54 \( \times {\rm{ 1}}{0^{ - {\rm{34}}}}\) J-sec
    Correct
2
An electron beam is subjected to a magnetic field of 2 \( \times {\rm{ 1}}{0^{ - {\rm{3}}}}\)T and an electric field of 3.4 \( \times {\rm{ 1}}{0^{\rm{4}}}{\rm{V}}{{\rm{m}}^{ - {\rm{1}}}}\) perpendicular to magnetic field. If the deviation of electrons is zero, the velocity of the beam is
  • A
    1.7 \( \times {\rm{ 1}}{0^{\rm{7}}}{\rm{m }}{{\rm{s}}^{ - {\rm{1}}}}\)
    Correct
  • B
    2.7 \( \times {\rm{ 1}}{0^{\rm{7}}}{\rm{m }}{{\rm{s}}^{ - {\rm{1}}}}\)
  • C
    7.1 \( \times {\rm{ 1}}{0^{\rm{7}}}{\rm{m }}{{\rm{s}}^{ - {\rm{1}}}}\)
  • D
    1.4 \( \times {\rm{ 1}}{0^{\rm{7}}}{\rm{m }}{{\rm{s}}^{ - {\rm{1}}}}\)
3
Uniform electric and magnetic fields are produced pointing in the same direction. An electron is projected pointing in the same direction, then
  • A
    the electron turns to left
  • B
    the velocity of electron increases
  • C
    the electron turns to right
  • D
    the velocity of electron decreases
    Correct
4
In Thomson’s method for finding specific charge of positive rays, the electric and magnetic fields are
  • A
    crossed and simultaneous
  • B
    Parallel and separate
    Correct
  • C
    Crossed and separate
  • D
    parallel and simultaneous
5
The specific charge for positive rays is much less than that for cathode rays. This is because
  • A
    experimental approach is defective
  • B
    their charge is very small
  • C
    their masses are very large
    Correct
  • D
    they are positively charged
6
The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV. The stopping potential is
  • A
    4 V
    Correct
  • B
    10 V
  • C
    2 V
  • D
    6 V
7
A stream of electrons enters an electric field with \({\rm{1}}{0^{\rm{7}}}{\rm{m }}{{\rm{s}}^{ - {\rm{1}}}}\) at right angle to it. If the strength of field is \({\rm{3 }} \times {\rm{ 1}}{0^{\rm{4}}}{\rm{V}}/{\rm{m}}\), the magnetic field acting perpendicular to electric field for producing no deflection of the beam is
  • A
    4 \( \times {\rm{ 1}}{0^{ - {\rm{3}}}}{\rm{T}}\)
  • B
    3.5 \( \times {\rm{ 1}}{0^{ - {\rm{3}}}}{\rm{T}}\)
  • C
    3 \( \times {\rm{ 1}}{0^{ - {\rm{3}}}}{\rm{T}}\)
    Correct
  • D
    0.3 \( \times {\rm{ 1}}{0^{ - {\rm{3}}}}{\rm{T}}\)
8
A drop of radius one micron carries a charge of 4 electrons. If the density of oil is 2g/cc, the electric field required to balance it is
  • A
    12.83 \( \times {\rm{ 1}}{0^{\rm{4}}}\) V/m
    Correct
  • B
    13.83 \( \times {\rm{ 1}}{0^{\rm{4}}}\) V/m
  • C
    12.03 \( \times {\rm{ 1}}{0^{\rm{4}}}\) V/m
  • D
    14.83 \( \times {\rm{ 1}}{0^{\rm{4}}}\) V/m
9
When a photon of energy 7eV is made incident on a metal then the emitted electron is stopped by a stopping potential of -5.5V. The work function of metal will be
  • A
    37.5 eV
  • B
    1.5 eV
    Correct
  • C
    -1.5 eV
  • D
    12.5 eV
10
In an experiment of photoelectric emission for incident light of 4000 \(\mathop A\limits^0 \), the stopping potential is 2V. If the wavelength of incident light is made 3000 \(\mathop A\limits^0 \), then stopping potential will be
  • A
    2 Volt
  • B
    zero
  • C
    more than 2 volt
    Correct
  • D
    less than 2 volt
11
Work function of tungsten and sodium are 4.4eV and 2.3 eV respectively. If threshold wavelength of sodium is 5460\(\mathop A\limits^0 \), then threshold wavelength of tungsten is
  • A
    6000 \(\mathop A\limits^0 \)
  • B
    11360 \(\mathop A\limits^0 \)
  • C
    2840 \(\mathop A\limits^0 \)
    Correct
  • D
    8000 \(\mathop A\limits^0 \)
12
in photoelectric effect, the photoelectric current
  • A
    does not depend on photon frequency but only on intensity of incident
    Correct
  • B
    decreases when frequency of incident photons increases
  • C
    both on intensity and frequency of incident beam
  • D
    increases when frequency of incident photons increases
13
If we consider electrons and photons of the same wavelength, then they will have the same
  • A
    angular momentum
    Correct
  • B
    velocity
  • C
    energy
  • D
    linear momentum
14
The work function of a metal is 4Ev. For emitting photoelectrons of zero velocity from the surface of this metal, the wavelength of incident light required must be
  • A
    1700 \(\mathop A\limits^0 \)
  • B
    2700 \(\mathop A\limits^0 \)
  • C
    3100 \(\mathop A\limits^0 \)
    Correct
  • D
    5900 \(\mathop A\limits^0 \)
15
The curve drawn between velocity and frequency of a photon in vacuum will be a
  • A
    straight line passing through origin and making an angle of \({\rm{45}}^\circ \) with frequency axis
  • B
    hyperbola
  • C
    straight line parallel to velocity axis
  • D
    straight line parallel to frequency axis
    Correct