Free Optics MCQs with Answers
665 Optics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
Last updated
665 questions · page 4 of 34
- A. Electromagnetic gun
- B. Source of electromagnetic waves
- C. Deflecting charged particle
- D. Converging source of electronsChoosing Binoculars For Bird Watching
Explanation: Electric and magnetic fields in an electron microscope control and focus the moving electrons in much the same way that glass lenses focus…
Correct answer: Converging source of electronsChoosing Binoculars For Bird Watching- A. Penetrating power is high
- B. Kinetic energy is large
- C. Wavelength is very short
- D. All the above reasons
Explanation: Energetic electrons have high momentum, and their de Broglie wavelength is λ = h/p, so increasing momentum makes the wavelength very…
Correct answer: Wavelength is very short- A. 9.5 x 10^15m
- B. 9.5 x 10^15sec
- C. 9.5 x 10^15Km
- D. 9.5 x 10^15cm
Explanation: A light-year is a distance, not a time: 1 light-year = speed of light × 1 year = (3.00 x 10^8 m s-1)(3.156 x 10^7 s) ≈ 9.46 x 10^15 m…
Correct answer: 9.5 x 10^15m- A. Isotropy
- B. Cleavage
- C. Homogeneity
- D. The external symmetry of form
Explanation: The external symmetry of form describes the repeated and consistent angular arrangement of the faces or cells of a crystal.
Correct answer: The external symmetry of form65. Which experiment shows that wavelength of light is smaller than that of sound___________________?
- A. Diffraction
- B. Polarization
- C. Interference
- D. Reflection
Explanation: Diffraction depends strongly on the ratio of wavelength to the size of the opening or obstacle.
Correct answer: Diffraction- A. Newton
- B. Einstein
- C. Michelson
- D. Galileo
Explanation: Albert A. Michelson used the known wavelength of red cadmium light in precision measurements of the metre.
Correct answer: Michelson- A. luminous
- B. non-luminous
- C. incandescent
- D. bright
Explanation: A luminous object produces and emits its own light, whereas a non-luminous object is visible only because it reflects light from another…
Correct answer: luminous- A. equally spaced
- B. distance between them increases
- C. distance between then decreases
- D. they are adjacent with no space in between
Explanation: In single-slit diffraction, the positions of minima satisfy a sin θ = mλ, so the angular separation between successive fringes decreases…
Correct answer: distance between then decreases- A. plane polarized
- B. un-polarized
- C. circularly polarized
- D. elliptically polarized
Explanation: A Polaroid transmits vibrations mainly along one transmission axis and absorbs the perpendicular component, so unpolarized light emerging…
Correct answer: plane polarized- A. 500 mm
- B. 5 x 10^-3 mm
- C. 2 x 10^-5 mm
- D. 2 x 10^-3 mm
Explanation: The grating element is the spacing between adjacent lines: d = 1/(500 lines mm-1) = 0.002 mm = 2 x 10^-3 mm.
Correct answer: 2 x 10^-3 mm- A. more for a round edge
- B. less for a round edge
- C. more for a sharp edge
- D. less for a sharp edge
Explanation: Diffraction is most noticeable at a sharp edge because the abrupt boundary causes waves to spread into the geometrical shadow.
Correct answer: more for a sharp edge- A. Newton
- B. Michelson
- C. Huygen
- D. Young
Explanation: Michelson made a highly accurate determination of the speed of light by using an improved rotating-mirror method and precise distance…
Correct answer: Michelson- A. 15 minutes
- B. 10 minutes
- C. 8 minutes
- D. 8 minutes 30 seconds
Explanation: Using t = distance/speed, t = 1.496 x 10^11 m / 3.00 x 10^8 m/s = 498.7 s = 8 min 18.7 s, approximately 8 min 20 s.
Correct answer: 8 minutes 30 seconds- A. sugar
- B. tartaric acid
- C. water
- D. sodium chlorate
Explanation: Optical activity means rotating the plane of polarization of light, which is associated with chiral substances.
Correct answer: water- A. Convex lens
- B. Interferometer
- C. Diffraction grating
- D. Concave
Explanation: The regularly spaced atomic planes in a crystal scatter waves in definite directions, so a crystal acts like a three-dimensional…
Correct answer: Diffraction grating76. In the shadow of a ball the central portion appears bright that happens due to_________________?
- A. Interference
- B. Diffraction
- C. Polarization
- D. Refraction
Explanation: The bright central spot behind a circular opaque ball is the Poisson or Arago spot, produced by diffraction and constructive interference…
Correct answer: Diffraction- A. black
- B. purple
- C. green
- D. no scientific reasoning available
Explanation: A blue book reflects mainly blue wavelengths, but red illumination provides almost no blue light to reflect, so the book appears black or…
Correct answer: black- A. radio waves
- B. ultraviolot rays
- C. X-rays
- D. sound waves
Explanation: Polarization is possible only for transverse waves because it restricts the direction of vibration perpendicular to propagation.
Correct answer: sound waves- A. vibration in all direction
- B. vibration in two mutually perpendicular directions
- C. vibration take place in a direction perpendicular to the direction of propagation of light
- D. no vibration at all
Explanation: In plane-polarized light, the electric field vibrates in one fixed direction that is perpendicular to the direction of propagation.
Correct answer: vibration take place in a direction perpendicular to the direction of propagation of light- A. 4 x 10^-10 m
- B. 2 x 10^-10 m
- C. 0.02 x 10^-10m
- D. 20 x 10^-10m
Explanation: Using Bragg's law, 2d sin θ = nλ. For d = 2 x 10^-10 m, θ = 30° and first order n = 1, λ = 2 x 2 x 10^-10 m x sin 30° / 1 = 2 x 10^-10 m.
Correct answer: 2 x 10^-10 m