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.
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665 questions · page 15 of 34
- A. Velocity
- B. Wavelength
- C. Amplitude
- D. Frequency
Explanation: Frequency is fixed by the source and remains unchanged when light enters a new medium; velocity and wavelength change according to the…
Correct answer: Frequency- A. I and II are correct only
- B. II and III correct only
- C. I and III are correct only
- D. I, II and III are correct
Explanation: Monochromaticity ensures single λ, coherence provides fixed phase relation, and linear superposition allows amplitudes to add - all three…
Correct answer: I, II and III are correct- A. Light from candle
- B. Light from simple lamp
- C. Light from sodium lamp
- D. Light from sun
Explanation: Sodium lamps emit light strongly at the sodium D‑lines near 589 nm, producing nearly monochromatic (narrowband) yellow light compared to…
Correct answer: Light from sodium lamp- A. (m+1/2) Dλ / d, where m=0,1,2,3,...
- B. (m-1/2) Dλ / d, where m=0,1,2,3,...
- C. m(D λ / d), where m=0,1,2,3,...
- D. (m+1/2) d / Dλ , where m=0,1,2,3,...
Explanation: Bright fringes occur at yₘ = mλD/d from the central maximum. This comes from constructive interference, d sinθ = mλ.
Correct answer: m(D λ / d), where m=0,1,2,3,...- A. Doubled
- B. Halved
- C. Four times
- D. One fourth
Explanation: β = λ D / d. If D → D/2 and d → 2d, new β' = λ (D/2) / (2d) = β/4. Thus, fringe spacing becomes one-fourth, option (d).
Correct answer: One fourth- A. At focus
- B. Between focus and center
- C. At center of curvature
- D. Behind the mirror
Explanation: For concave mirrors, when the object is at the centre of curvature (C), the image is formed at C - real, inverted, and of the same size.
Correct answer: At center of curvature- A. 19.5°
- B. 22.0°
- C. 25.0°
- D. 28.5°
Explanation: Snell's law: n₁ sin θ₁ = n₂ sin θ₂. 1 × sin 30° = 1.5 × sin θ₂, 0.5 = 1.5 sin θ₂, sin θ₂ = 0.333, θ₂ = arcsin(0.333) ≈ 19.5°.
Correct answer: 19.5°- A. Infinity
- B. Zero
- C. Equal to radius of curvature
- D. None
Explanation: A plane mirror has no curvature (R = ∞), hence focal length f = R/2 = ∞.
Correct answer: Infinity- A. Reflection
- B. Refraction
- C. Total internal reflection
- D. Transmission
Explanation: Total internal reflection is the phenomenon by which light propagates through an optical fibre.
Correct answer: Total internal reflection- A. Red
- B. Violet
- C. Blue
- D. Green
Explanation: Red light has the longest wavelength and lowest refractive index, so it bends the least when passing through a prism.
Correct answer: Red- A. Erect
- B. Inverted
- C. Magnified
- D. Diminished
Explanation: A convex lens forms a real and inverted image when the object is placed at the 2F point.
Correct answer: Inverted- A. Magnifying Power of the telescope
- B. Width of the telescope
- C. Length of the telescope
- D. Height of the telescope
Explanation: The tube length g is the distance between the secondary focal point of the objective and the primary focal point of the eyepiece.
Correct answer: Length of the telescope- A. 60°
- B. 45°
- C. 90°
- D. 180°
Explanation: When the incident ray and reflected ray are parallel, the angle between the mirrors is always 90° due to the Law of Reflection and…
Correct answer: 90°- A. ABC
- B. ADC
- C. AFC
- D. AEC
Explanation: Path AFC minimizes path length by utilizing the principles of reflection and refraction effectively, making it the correct choice.
Correct answer: AFC- A. Always bright
- B. Always dark
- C. Either dark or bright depending on the position of S
- D. Neither dark nor bright
Explanation: The central fringe can vary in brightness based on the position of the slits.
Correct answer: Either dark or bright depending on the position of S- A. Monochromatic
- B. Bichromatic
- C. Multichromatic
- D. Non chromatic
Explanation: Laser light is monochromatic, directional, and coherent. Lasers are known for producing light that is highly monochromatic, meaning it…
Correct answer: Monochromatic- A. Remains same
- B. Reduce to one half
- C. Reduce to one quarter
- D. Increase to twice
Explanation: n=λD/dIf the slit spacing (d) is doubled and the distance between the slit and screen(D) is halved.
Correct answer: Reduce to one quarter- A. Reflection
- B. Refraction
- C. Total internal reflection
- D. Transmission
Explanation: Total internal reflection (TIR) is the optical phenomenon in which waves, such as light, are completely reflected under certain conditions…
Correct answer: Total internal reflection- A. Proton
- B. Neutron
- C. Electron
- D. Alpha particle
Explanation: The wavelength of a particle is inversely proportional to its momentum.
Correct answer: Electron- A. Iconography
- B. Holography
- C. Logography
- D. Photography
Explanation: Holography is the process of producing holograms,which are three dimensional objects. Holography is sometimes called lensless photography.
Correct answer: Holography