Class 12 Wave Optics CBSE Questions & Answers

Class 12 · Wave Optics

This is Physics Class 12 Wave Optics CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Referring to the Young’s double slit experiment, Phase difference corresponding to a Path Difference of \(\lambda \) /3 is
  • A
    \({\rm{9}}0^\circ \)DC
  • B
    \({\rm{18}}0^\circ \)
  • C
    \({\rm{6}}0^\circ \)
  • D
    \({\rm{12}}0^\circ \)
    Correct
2
Referring to the Young’s double slit experiment, Path Difference corresponding to a Phase difference of π/3 is
  • A
    \(\lambda \)/3
  • B
    \(\lambda \)/6
    Correct
  • C
    \(\lambda \)/5
  • D
    \(\lambda \)/4
3
Referring to the Young’s double slit experiment, if D and d are distance from slit to screen and screen center to point P fringe width is given by
  • A
    \(\lambda {\rm{D}}/{\rm{2d}}\)
  • B
    \({\rm{3}}\lambda {\rm{D}}/{\rm{d}}\)
  • C
    \(\lambda {\rm{D}}/{\rm{d}}\)
    Correct
  • D
    \({\rm{2}}\lambda {\rm{D}}/{\rm{d}}\)
4
In general the term diffraction is used
  • A
    None of the above
  • B
    if two sources are added vectorially
  • C
    if large number of sources is added vectorially
    Correct
  • D
    if single source is multiplied by scalar
5
Diffraction also refers to
  • A
    the bonding of light to an obstacle
  • B
    None of the above
  • C
    the bending of light in a medium
  • D
    the bending of light around an obstacle
    Correct
6
In the single slit diffraction every point on the slit acts
  • A
    to increase intensity
  • B
    as a secondary source
    Correct
  • C
    None of the above
  • D
    to reduce intensity
7
In the single slit diffraction the screen is at a large distance compared to slit width the different rays from the slit would be
  • A
    None of the above
  • B
    parallel
    Correct
  • C
    anti parallel
  • D
    perpendicular
8
In the single slit diffraction the screen is at a large distance compared to slit width and \(\theta \) is the angle between straight line joining the center of the screen to center of slit and center of slit to the point of observation, a is slit width, maxima are got at \(\theta \) =
  • A
    (n +\({1 \over 2}){\lambda \over a}\)
    Correct
  • B
    (n +\({1 \over 2}){{2\lambda } \over a}\)
  • C
    (n +\({1 \over 3}){\lambda \over a}\)
  • D
    (n + \({1 \over 2}){\lambda \over 2}\)
9
Which of the following phenomenon cannot be explained by diffraction?
  • A
    The rainbow fringes of an oil slick on water
    Correct
  • B
    lack of sharp boundary when a point source of light illuminates a straightedge
  • C
    fringes observed from a large number of parallel slits
  • D
    A bulb filament viewed through two blades held so that the edges form a slit
10
If two stars have an angular separation of \(\Delta \theta \) and ‘a’ is the radius of the telescope aperture, then the angular resolution (for the stars to appear separate) is given by the expression
  • A
    \({{0.67\lambda } \over a}\)
  • B
    \({{0.91\lambda } \over a}\)
  • C
    \({{0.81\lambda } \over a}\)
  • D
    \({{0.61\lambda } \over a}\)
    Correct
11
If D and f are the objective diameter, and focal length, Minimum separation, \({{\rm{d}}_{{\rm{min}}}}\), in the object plane of a compound microscope that can be resolved is given by
  • A
    \({{1.52f\lambda } \over D}\)
  • B
    \({{1.62f\lambda } \over D}\)
  • C
    \({{1.22f\lambda } \over D}\)
    Correct
  • D
    \({{1.32f\lambda } \over D}\)
12
If ‘a’ is aperture size (i.e., slit or hole) and λ the wave length formula for Fresnel distance is
  • A
    \({\lambda ^{\rm{2}}}/{\rm{2a}}\)
  • B
    \({{\rm{a}}^{\rm{2}}}/{\rm{2}}\lambda \)
  • C
    \({\lambda ^{\rm{2}}}/{\rm{a}}\)
  • D
    \({{\rm{a}}^{\rm{2}}}/\lambda \)
    Correct
13
For distances much greater than Fresnel distance ZF
  • A
    spreading due to diffraction is small
  • B
    spreading due to diffraction dominates over that due to ray optics
    Correct
  • C
    No diffraction is observed
  • D
    None of the above
14
We say that a light wave is linearly polarized in y direction if
  • A
    the wave is stationary
  • B
    the wave has only z displacements
  • C
    the wave has only x displacements
  • D
    the wave has only y displacements
    Correct
15
If \({{\rm{I}}_0}\) is the intensity after the first Polaroid the intensity emerging from the second Polaroid kept at an angle \(\theta \) to the first is given by
  • A
    \({{\rm{I}}_0}{\rm{cos}}\theta \)
  • B
    \({{\rm{I}}_0}{\rm{co}}{{\rm{s}}^{\rm{2}}}\theta \)
    Correct
  • C
    \({{\rm{I}}_0}{\rm{co}}{{\rm{s}}^{\rm{2}}}\theta /{\rm{2}}\)
  • D
    \({\rm{2}}{{\rm{I}}_0}{\rm{co}}{{\rm{s}}^{\rm{2}}}\theta \)