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 12 of 34
- A. ¼ times
- B. 4 times
- C. Twice
- D. ½ of 8 cm diameter pipe
Explanation: The velocity of flow of water in a pipe is inversely proportional to the square of its diameter, according to the principle of…
Correct answer: 4 times- A. 50lb/ft2
- B. 50ft/lb
- C. 50ft/lb3
- D. 50lb/ft3
Explanation: In the F.P.S. (Foot-Pound-Second) system, the density of water is commonly expressed in pounds per cubic foot (lb/ft3).
Correct answer: 50lb/ft3- A. 1000 kg
- B. 2000kg
- C. 4000kg
- D. 8000 kg
Explanation: The total pressure on a vertical gate submerged in water can be calculated using the hydrostatic pressure formula:P=ρ⋅g⋅h⋅AThe total…
Correct answer: 2000kg- A. Source
- B. Source of wave front
- C. Source of secondary wave front
- D. None
Explanation: When a wavefront, which is an imaginary surface representing points in a wave that are in phase (e.g., crest or trough of a light wave)…
Correct answer: Source of secondary wave front- A. Electromagnetic
- B. Longitudinal
- C. Mechanical waves
- D. Matter waves
Explanation: Polarization is a phenomenon related to the orientation of the electric field vector of a wave.
Correct answer: Electromagnetic- A. Longer wavelength light
- B. Shorter wavelength
- C. Wavelength has no effect
- D. It depends only on the design of the microscope, not on light
Explanation: Shorter wavelengths improve resolution and clarity in microscopy
Correct answer: Shorter wavelength- A. Wavelength of light
- B. Speed of light
- C. Frequency of light
- D. Wavelength and speed of light
Explanation: When light enters a denser medium like glass from air, it slows down, resulting in a change in the speed of light.
Correct answer: Wavelength and speed of light- A. Frequency of light
- B. Wavelength of light
- C. Speed of light
- D. All of these
Explanation: The frequency of light remains constant when it passes from one medium to another.
Correct answer: Frequency of light- A. 0.5
- B. 10
- C. 20
- D. 0.05
Explanation: The magnifying power of a telescope is given by the formula: Magnifying power = (Focal length of objective lens) / (Focal length of…
Correct answer: 20- A. Interface
- B. Diffraction
- C. Polarization
- D. Dispersion
Explanation: Diffraction is the bending of waves around obstacles or through openings.
Correct answer: Diffraction- A. Reflected away from normal
- B. Reflected towards normal
- C. Refracted towards normal
- D. Refracted away from normal
Explanation: When a wave enters a denser medium, its speed decreases. This change in speed causes the wave to bend towards the normal.
Correct answer: Refracted towards normal- A. Red
- B. Blue
- C. Green
- D. Yellow
Explanation: The human eye is most sensitive to the green portion of the visible light spectrum.
Correct answer: Green- A. Transmit
- B. Reflect
- C. Refract
- D. Absorb
Explanation: When a red colored cloth is exposed to red light, the cloth will reflect the red light.
Correct answer: Reflect- A. Neutrons
- B. Alpha particles
- C. Gamma rays
- D. Laser
- E. All of these
Explanation: The particles with high ionizing capacity will affect the eye tissues. Among the given, alpha particles and gamma rays are highly ionizing…
Correct answer: All of these- A. 4 diopter
- B. 6 diopter
- C. 8 diopter
- D. 10 diopter
Explanation: Lens powers add algebraically for thin lenses in contact: Ptotal= P1 + P2.
Correct answer: 4 diopter- A. The frequency increases and the wavelength decreases
- B. The frequency decreases and the wavelength increases
- C. The frequency does not change, but the wavelength decreases
- D. The frequency does not change, but the wavelength increases
Explanation: At a boundary, the wave frequency remains fixed by the source; the wave speed reduces in the denser medium, so the wavelength shortens (v…
Correct answer: The frequency does not change, but the wavelength decreases- A. Increase the focal length of the lens (lens and position of object is fixed)
- B. Insert a diverging lens between the lens and the screen (converging lens and position of object is fixed)
- C. Increase the distance of the object from the lens
- D. Move the object closer to the lens
Explanation: To make the image nearer to the lens, you should move the object closer to it.
Correct answer: Move the object closer to the lens- A. 3.2 mm
- B. 1.63 mm
- C. 0.585 mm
- D. 2.31 mm
Explanation: Fringe position y = m λ D / d (bright) and dark at (m+½)λD/d. Compute positions for third dark (m=2 dark → y = (2.5)λD/d) and fifth bright…
Correct answer: 1.63 mm- A. 12 x 10^-6 m
- B. 12 x 10^-7 m
- C. 12 x 10^-8 m
- D. 12 x 10^-9 m
Explanation: Angular width = 2θ = 30°∴ sin 30° = λ / a∴ a = λ / sin 30°= 6000 × 10⁻¹⁰ / sin 30°= 6000 × 10⁻¹⁰ / 1/2= 12000 × 10⁻¹⁰ m= 12 × 10⁻⁷ m
Correct answer: 12 x 10^-7 m- A. 14.73 mm
- B. 14.73 cm
- C. 1.473 mm
- D. 147.3 mm
Explanation: Fringe spacing β = λD/d = (5893×10⁻¹⁰ m × 2 m)/(0.8×10⁻³ m) ≈ 1.473×10⁻³ m = 1.473 mm. So option (C) is the correct fringe separation.
Correct answer: 1.473 mm