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COMEDK Wave Optics — practice questions

Explore 56 free Wave Optics questions in COMEDK Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Wave Optics questions and exercises with answers

Showing questions 1–30 of 56.

Two light sources can produce sustained interference fringes on a screen only if they are:Read the answer and worked solution →Snell's law states that the ratio sin(i)/sin(r) for two media is:Read the answer and worked solution →The wavefront from a point source is:Read the answer and worked solution →Young's double-slit experiment demonstrates which phenomenon?Read the answer and worked solution →Two waves with the same frequency and constant phase difference are called:Read the answer and worked solution →In Young's double-slit experiment, the bright fringe condition is path difference equals:Read the answer and worked solution →Polarization of light is possible because light is:Read the answer and worked solution →In Young's experiment, fringe width β equals:Read the answer and worked solution →In Young's experiment with d = 1 mm, D = 1 m, light wavelength 600 nm, fringe width is:Read the answer and worked solution →When light goes from a less dense to denser medium (e.g., air to water), it bends:Read the answer and worked solution →Critical angle for total internal reflection from water (n = 4/3) to air:Read the answer and worked solution →In a thin film of thickness t with refractive index n, condition for destructive interference for reflected light (no phase change on reflection conditions):Read the answer and worked solution →Diffraction is the:Read the answer and worked solution →Single-slit diffraction first minimum occurs at angle θ where:Read the answer and worked solution →Brewster's angle θ_B for light hitting glass (n = 1.5) from air satisfies:Read the answer and worked solution →For maximum brightness in Newton's rings (reflected light, air film), what is the radius of n-th bright ring? (R = lens radius, λ = wavelength)Read the answer and worked solution →Two slits 0.5 mm apart with light of wavelength 5000 Å. The 5th bright fringe is at distance from central maximum on screen 1 m away:Read the answer and worked solution →In Young's experiment, if the entire setup is immersed in water (n = 4/3), the fringe width:Read the answer and worked solution →Power of a convex lens of focal length 50 cm:Read the answer and worked solution →Resolution limit of a telescope by Rayleigh criterion:Read the answer and worked solution →Wavelength of light in water (n = 4/3) if its vacuum wavelength is 600 nm:Read the answer and worked solution →Two coherent sources have intensities I1 = 9I and I2 = I. Maximum and minimum intensities in interference pattern:Read the answer and worked solution →In Young's experiment, intensity at a point where path difference is λ/4:Read the answer and worked solution →For a grating with 500 lines/mm and light at 600 nm, find angle for the first-order maximum:Read the answer and worked solution →In single-slit diffraction, ratio of intensities of first and central maxima is approximately:Read the answer and worked solution →Speed of light in a medium of refractive index 1.5 is:Read the answer and worked solution →A wavefront is:Read the answer and worked solution →Young's double-slit experiment demonstrates:Read the answer and worked solution →For constructive interference, path difference Δp =Read the answer and worked solution →In YDSE, fringe width β =Read the answer and worked solution →

Worked practice questions

Two light sources can produce sustained interference fringes on a screen only if they are:

  1. Coherent (constant phase difference)
  2. Of identical intensity
  3. From the same physical lamp
  4. Polarised in the same direction
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Correct answer: A. Coherent (constant phase difference)

Sustained interference needs sources with a constant phase relationship over time, which is what coherence means. Two ordinary lamps emit light with phases that vary randomly at $10^{-8}$ s scale so their interference pattern washes out almost instantly. The two slits in Young's experiment achieve coherence because both are illuminated by the same primary source, inheriting its phase. Equal intensity (B) improves fringe contrast but is not required. Same lamp (C) is one way to ensure coherence but not the only way (e.g. laser pairs). Polarisation alignment (D) matters for contrast, not for the existence of fringes.

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Snell's law states that the ratio sin(i)/sin(r) for two media is:

  1. Variable
  2. Constant for given media
  3. Equal to 1
  4. Equal to 0
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Correct answer: B. Constant for given media

sin(i)/sin(r) = n21, the refractive index of medium 2 relative to medium 1. This ratio is constant for any pair of media.

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The wavefront from a point source is:

  1. Planar
  2. Spherical
  3. Cylindrical
  4. Cuboidal
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Correct answer: B. Spherical

Light from a point source spreads out in all directions, so wavefronts are concentric spheres centered on the source.

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