WBCS Mains Physics Optics Questions 2023

Q10. When light is refracted, which of the following does not change?

(A) Wavelength
(B) Frequency
(C) Velocity
(D) Amplitude

Correct Answer: (B) Frequency

Q143. What is the source of UV radiation?

(A) Hydrogen gas discharge lamp
(B) RF oscillator
(C) Klystron oscillator
(D) Nernst filament

Correct Answer: (A) Hydrogen gas discharge lamp

Q165. When the power of the eye lens increases, the defect of vision produced is known as

(A) Shortsightedness
(B) Longsightedness
(C) Colour blindness
(D) Astigmatism

Correct Answer: (A) Shortsightedness

Q167. An astronaut in a spaceship sees the outer space as

(A) Red
(B) Blue
(C) Indigo
(D) Black

Correct Answer: (D) Black

Q182. The range of visible spectrum is

(A) 350–650 nm
(B) 380–750 nm
(C) 390–700 nm
(D) 400–800 nm

Correct Answer: (B) 380–750 nm

WBCS Mains Physics Optics Questions 2022

Q81. Polarization of light proves the

(A) Longitudinal nature of light
(B) Quantum nature of light
(C) Corpuscular nature of light
(D) Transverse nature of light

Correct Answer: (D) Transverse nature of light

Q117. The blueness of the sky is mainly due to

(A) The scattering of sunlight by air molecules.
(B) The presence of water vapor.
(C) Absorption of blue light by the air.
(D) Emission of blue light by the atmosphere.

Correct Answer: (A) The scattering of sunlight by air molecules.

WBCS Mains Physics Optics Questions 2021

Q46. A thin oil film on a water surface appears coloured because of

(A) Reflection
(B) Refraction
(C) Interference
(D) Polarization

Correct Answer: (C) Interference

Q78. The colour of a star indicates its

(A) Weight
(B) Size
(C) Distance
(D) Temperature

Correct Answer: (D) Temperature

Q152. The splitting of white light into its components is due to

(A) Reflection
(B) Refraction
(C) Transmission
(D) Dispersion

Correct Answer: (D) Dispersion

WBCS Mains Physics Optics Questions 2020

Q29. The quanta of light is called

(A) Proton
(B) Photon
(C) Phonon
(D) Neutron

Correct Answer: (B) Photon

Q49. The stars twinkle because of

(A) Reflection
(B) Refraction
(C) Diffraction
(D) Interference

Correct Answer: (B) Refraction

Q55. When light is refracted, which of the following does not change?

(A) Frequency
(B) Wavelength
(C) Velocity
(D) Amplitude

Correct Answer: (A) Frequency

WBCS Mains Physics Optics Questions 2018

Q44. Wavelength of visible light lies in between

(A) 400 to 800 nm
(B) 500 to 1000 nm
(C) 300 to 600 nm
(D) 200 to 400 nm

Correct Answer: (A) 400 to 800 nm

Q93. Solar spectrum is the example of

(A) Continuous emission spectrum
(B) Band absorption spectrum
(C) Line absorption spectrum
(D) Continuous absorption spectrum

Correct Answer: (C) Line absorption spectrum

WBCS Mains Physics Optics Questions 2017

Q158. Refractive index of a medium is defined by

(A) The ratio of the cosine of the angles of incidence and refraction of light is constant when it passes between two given media.
(B) The ratio of the sine of the angles of refraction and incidence of light is constant when it passes between two given media.
(C) The ratio of the sine of the angles of incidence and refraction of light is constant when it passes between two given media.
(D) None of the above.

Correct Answer: (C) The ratio of the sine of the angles of incidence and refraction of light is constant when it passes between two given media.

Q199. Line spectrum is produced by

(A) The Sun
(B) Mercury vapour lamp
(C) Candle
(D) Electric bulb

Correct Answer: (B) Mercury vapour lamp

WBCS Mains Physics Optics Questions 2016

Q7. When viewed in white light, soap bubbles show colours because of

(A) Scattering
(B) Diffraction
(C) Interference
(D) Dispersion

Correct Answer: (C) Interference

Q15. Which one among the following has the highest energy?

(A) Blue light
(B) Green light
(C) Red light
(D) Yellow light

Correct Answer: (A) Blue light

Q16. Cylindrical lens is used by a person suffering from

(A) Astigmatism
(B) Myopia
(C) Hypermetropia
(D) Presbyopia

Correct Answer: (A) Astigmatism

Q17. To an observer on the lunar surface, during the daytime the sky will appear to be

(A) Light yellow
(B) Orange
(C) Blue
(D) Black

Correct Answer: (D) Black

WBCS Mains Physics Optics Questions 2015

Q43. Blue colour of the sky is due to the phenomenon of

(A) Scattering
(B) Dispersion
(C) Reflection
(D) Refraction

Correct Answer: (A) Scattering

Q51. Diffusion of light in the atmosphere takes place due to

(A) Dust particles
(B) Carbon dioxide
(C) Helium
(D) Water vapours

Correct Answer: (A) Dust particles

Q56. Which one of the following reflects back more sunlight as compared to the other three?

(A) Sand desert
(B) Paddy crop land
(C) Land covered with fresh snow
(D) Prairie grass land

Correct Answer: (C) Land covered with fresh snow

Q57. Rainbow is produced when sunlight falls on drops of rain. The physical phenomena responsible for this are (1) Dispersion, (2) Refraction, (3) Internal reflection.

(A) 1 & 2
(B) 2 & 3
(C) 1 & 3
(D) All of the above

Correct Answer: (D) All of the above

Q114. Several colours on the screen of a colour television are produced by mixing lights of colours

(A) Red, Yellow, Green
(B) Red, Yellow, Blue
(C) Red, Green, Blue
(D) Yellow, Green, Blue

Correct Answer: (C) Red, Green, Blue

WBCS Mains Physics Optics Questions 2014

Q11. The wavelength of visible light lies between

(A) 200–400 nm
(B) 400–700 nm
(C) 700–1000 nm
(D) 1000–2000 nm

Correct Answer: (B) 400–700 nm