Quiz  /  Wave Optics Class 12 MCQ Questions With Answers

  • 1. 
    A diffraction grating that has 2000 slits per centimetre is used to measure the wavelengths emitted by hydrogen gas. At what angle in the first order spectrum would you expect to find the violet line that has a wavelength of 434 nm?

  • 3°3\degree3°
  • 5°5\degree5°
  • 7°7\degree7°
  • 9°9\degree9°

  • 2. 
    Total internal reflection only occurs when light tries to travels from a medium with a _____ index to ____ index

  • lower to higher
  • higher to lower
  • same to same

  • 3. 
    Dimensions for a point source are important.

  • True
  • False

  • 4. 
    If it takes a waves 2.0 s to travel a distance of 10 meters, what is the wave speed?

  • 0.2 m/s
  • 5 m/s
  • 12 m/s
  • 20 m/s

  • 5. 
    What must be true about waves which reflect off of fixed boundaries?

  • Their amplitude increases.
  • Their wavelength increases.
  • They become inverted.
  • They remain erect.

  • 6. 
    If a wave from one slit of a Young's double-slit experiment set-up arrives at a point on the screen one wavelength behind the wave from the other slit, what is observed at that point?

  • dark fringe
  • bright fringe
  • multi-colored fringe
  • gray fringe, neither bright nor dark

  • 7. 
    When light travels from air into another medium with a higher index of refraction, what happens to the speed at which it travels.

  • it increases
  • it decreases
  • it remains constant
  • this is impossible

  • 8. 
    ______________________ occurs when waves combine to create a wave with a LOWER amplitude.

  • Diffraction
  • Constructive interference
  • Destructive interference
  • Refraction

  • 9. 
    For diffraction at a single Slit, the angular position for nth secondary maxima is

  • θ=nλ\theta=n\lambdaθ=nλ
  • θ= nλa\theta=\ \frac{n\lambda}{a}θ= anλ​
  • θ= (n+12)λa\theta=\ \left(n+\frac{1}{2}\right)\frac{\lambda}{a}θ= (n+21​)aλ​
  • θ= naλ\theta=\ \frac{na}{\lambda}θ= λna​

  • 10. 
    Bending of light at sharp edges of obstacles is due to

  • polarization
  • diffraction
  • refraction
  • interference

  • 11. 
    A point source of light creates..... ........... wavefront

  • cylindrical
  • plane
  • spherical
  • parabolic

  • 12. 
    As per Huygens principle, wavelets originating on a wavefront grow with

  • slow speed
  • same speed
  • more speed
  • none of these

  • 13. 
    LCD uses the phenomenon of

  • dispersion
  • diffraction
  • interference
  • polarization

  • 14. 
    In youngs double slit experiment if entire apparatus is immersed in water the fridge width would

  • decrease
  • increase
  • not change
  • none of the above

  • 15. 
    If on rotating an analyser there no variation in the intensity of light then the light is

  • plane polarized
  • unpolarized
  • partially polarized
  • extra ordinary

  • 16. 
    The height of a wave from the undisturbed state is called

  • frequency
  • amplitude
  • period
  • crest

  • 17. 
    The dual nature of light is exhibited?

  • diffraction and photoelectric effect
  • photoelectric effect
  • refraction & interference
  • diffraction & reflection

  • 18. 
    Superposition of family of waves originating from a slit forms......... pattern

  • interference
  • diffraction
  • polarization
  • dispersion

  • 19. 
    The angle of incidence at which reflected light is totally polarised for reflection from air to glass ( refractive index n)

  • sin-1 (n)
  • sin-1 (1 / n)
  • tan-1 (1 / n)
  • tan-1 (n)

  • 20. 
    What is path difference for destructive interference?

  • (a) nλ
  • (b) n(λ +1)
  • (c) (2n + 1)λ/2
  • (d) (n +1)λ/2

  • 21. 
    Which of the following phenomenon is not explained by Huygen’s wave theory?

  • Diffraction
  • Interference
  • Polarisation
  • Photoelectric effect

  • 22. 
    For diffraction at a single Slit, the angular position for nth minimum is

  • θ=nλ\theta=n\lambdaθ=nλ
  • θ= nλa\theta=\ \frac{n\lambda}{a}θ= anλ​
  • θ= (n+12)λa\theta=\ \left(n+\frac{1}{2}\right)\frac{\lambda}{a}θ= (n+21​)aλ​
  • θ= naλ\theta=\ \frac{na}{\lambda}θ= λna​
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