Physics Class 12 MCQ Wave Optics – Chapter 10

Ques 1: A plane wave passes through a convex lens. The geometrical shape of the wavefront that emerges is

• plane
• diverging spherical
• converging spherical
• none of these

converging spherical

Ques 2: When a wave undergoes reflection at a denser medium, its phase changes by

• 0⁰
• 45⁰
• 90⁰
• 180⁰

180⁰

Ques 3: In YDSE, when separation between two slits is increased, fringe width

• decreases
• increases
• remains the same
• none of these

decreases

Ques 4: Three lights, red, violet and green are used successively in YDSE. Fringe width will be maximum for

• red
• violet
• green
• same for all

red

Ques 5: In YDSE, the intensity of central maximum is l. What will be the intensity at the same place when one of the slits is closed?

• I
• I/2
• I/4
• 2 I

I/4

Ques 6: What is the ratio of slit widths when amplitudes of light waves from them has a ratio 1:√2 ?

• 1 : √2
• √2 : 1
• 1 : 2
• 2 : 1

1 : 2

Ques 7: For an aperture of 2 mm and wavelength of 500 nm. Fresnel distance is

• 5 m
• 8 m
• 10 m
• 40 m

8 m

Ques 8: When diameter of objective of an astronomical telescope is doubled, its limit of resolution is

• doubled
• quadrupled
• halved
• unaffected

halved

Ques 9: Polarizing angle for a medium is 60⁰. Its refractive index is

• 1.732
• 1
• 1.414
• 2

1.732

Ques 10: Which one of the following cannot be polarized ?

• X-rays
• radio waves
• sound waves
• light waves

sound waves

Ques 11: Which one of the following phenomena confirms that light waves are transverse ?

• interference
• diffraction
• dispersion
• polarization

polarization

Ques 12: A rays of light falls on a transparent slab of μ = 1.0. If reflected and refracted rays are mutually perpendicular, what is the angle of incidence ?

• 45⁰
• 60⁰
• 30⁰
• 90⁰

45⁰

Ques 13: The angle between pass axis of polarizer and analyzer is 45⁰. The percentage of polarized light passing through analyzer is

• 100%
• 50%
• 25%
• 75%

50%

Ques 14: Unpolarized beam of light of intensity I₀ is incident on a polarizer P₁. Another polarizer P₂ is held parallel to it such that its pass axis is oriented at an angle 60⁰, then what percentage of light will emerge from the system :

• 30%
• 100%
• 12.5%
• 37.5%

12.5%

Ques 15: In a Young’s double slit experiment, the separation between the slits is 0.1 mm, the wavelength of light used is 600 nm and the interference pattern is observed on a screen 1 m away. Find the separation between bright fringes.

• • 6.6 mm
  • 6.0 mm
  • 6 m
  • 60 cm

  6.0 mm

Ques 16: Om the Young’s double slit experiment, the fringe pattern as seen on the screen is :

• parabola
• Hyperbola
• ellipse
• Spiral

Hyperbola

Ques 17: The light source used in Young’s bouble slit experiment are

• Incoherent
• Coherent
• White light
• Blue-green-red light

Coherent

Ques 18: What is the effect on the angular width of interference fringes in a Young’s double slit experiment when the screen is moved near to the plane of slits.

• Increases
• Decreases
• Constant
• Not defined

Constant

Ques 19: The phase difference between two waves at the place of constructive interference is given as a

• multiple of π
• multiple of (2n-1)π
• even multiple of π
• odd multiple of π

even multiple of π

Ques 20: The path difference between two waves at the place of destructive interference is given by :

• multiple of λ
• multiple of λ/2
• even multiple of λ/2
• odd multiple of λ/2

odd multiple of λ/2

Ques 21: Resolving Power of Microscope depends upon

• Focal Length
• Wavelength
• Diameter
• Wavelength, Diameter of lens

Wavelength, Diameter of lens

Ques 22: Angular width of interference fringe depends on

• Distance between Slit and Screen
• Wavelength of light
• Ration of the wavelength and Slit width
• Width of Slit

Wavelength of light

Ques 23: Resolving Power of the telescope depends upon the

• Diameter of circular aperture
• Focal length
• Magnification power
• Refractive index

Diameter of circular aperture

Ques 24: In teh phenomena of Diffraction of light when the violet light is used in the experiment instead of red light then

• Fringe width increases
• No change in fridge width
• Fringe width decreases
• Colour pattern is formed

Fringe width decreases

Ques 25: Diffraction aspect is easier to notice in case of the sound waves than in case of the light waves because sound waves

• Have longer wavelength
• Shorter wavelength
• Longitudinal wave
• Transverse waves

Have longer wavelength

Ques 26: The wave-front due to source situated at infinity is

• Spherical
• plane
• Cylindrical
• Rectangular

plane

Ques 27: Colours apearing on a thin film of a soap bubble are due to

• Diffraction
• Refraction
• Dispersion
• Interference

Interference

Ques 28: For an aperture of size (d) illuminated by a parallel beam of light having wavelength λ, the Fresnel’s distance is

• Z = d²/λ
• Z = d/λ
• Z = d/λ²
• Z = dλ

Z = d²/λ

Ques 29: Unpolarized light is incident on a plane glass surface having refractive index √3. The angle of incidence at which reflected and refracted rays would become perpendicular to each other is

• 15⁰
• 30⁰
• 45⁰
• 60⁰

60⁰

Ques 30: The shape of interference fringes in YDSE, when distance between slit and screen is very large as compared to fringe width is

• straight lines
• parabolic
• circular
• hyperbolic

straight lines