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Light

198 MCQ questions with answers and explanations · page 8 of 8

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Q176. In which year did Ole Rømer measure the speed of light for the first time in history?

  1. A1776 AD
  2. B1676 AD
  3. C1876
  4. D1867 AD
Show answer & explanation

Answer: B) 1676 AD

Q177. Which instrument is used in submarines to see objects above sea level?

  1. Apyrometer
  2. BEpidiascope
  3. CPereskop
  4. Dodometer
Show answer & explanation

Answer: C) Pereskop

Q178. Which secondary color is obtained by mixing two primary colors, red and blue?

  1. AWhite
  2. BYellow
  3. CMagenta
  4. DCyan
Show answer & explanation

Answer: C) Magenta

Q179. We see the colour of grass as green because-

  1. AIt reflects green light back to our eyes.
  2. BIt reflects white light onto our eyes.
  3. CIt reflects all light except green.
  4. DIt absorbs green light
Show answer & explanation

Answer: A) It reflects green light back to our eyes.

Q180. Which of the following statements is not correct for light rays?

  1. Alight travels at different speeds in different media
  2. BLight travels in air at a speed of about 300 million meters per second
  3. CAs light leaves the surface of water and enters the air, its speed slows down
  4. DAs light leaves the glass surface and enters the air, its speed increases
Show answer & explanation

Answer: C) As light leaves the surface of water and enters the air, its speed slows down

Q181. When light passes from one medium to another, which of the following does/does not change?

  1. AVelocity
  2. Bwavelength
  3. Cfrequency
  4. DRefractive index E None of the above / More than one of the above
Show answer & explanation

Answer: C) frequency

Q182. If a ray of light enters from a rarer medium to a denser medium at zero angle of incidence, then it-

  1. Awill be reflected back
  2. Bwill go straight
  3. Cwill turn right
  4. Dwill turn at 45°
Show answer & explanation

Answer: B) will go straight

Q183. The image we see in a plane mirror is-

  1. Ais real and therefore can be photographed
  2. Bis virtual and is closer than the object
  3. Cis virtual and is laterally inverted
  4. DIt is real and cannot be photographed.
Show answer & explanation

Answer: C) is virtual and is laterally inverted

Q184. What will be the angle of refraction for a ray of light entering the glass medium from water at an angle of incidence of 0°?

  1. A90°
  2. B45°
  3. C0°
  4. DThe rays will not penetrate at all.
Show answer & explanation

Answer: C) 0°

Q185. The correct relation between the radius of curvature r and the focal length of a spherical mirror is-

  1. ARf
  2. BR-2f
  3. CR=3f
  4. DR=4f
Show answer & explanation

Answer: B) R-2f

Q186. Which of the following is correct regarding the formula 1/f=1/v=1/u according to the Cartesian sign convention, where the symbols have their usual meanings?

  1. AThis applies only to spherical mirrors.
  2. BThis applies only to spherical lenses.
  3. CThis applies to spherical mirrors as well as spherical lenses.
  4. DThis is an invalid formula lens, concave, and has a focal length of 2.0 m.
Show answer & explanation

Answer: A) This applies only to spherical mirrors.

Q187. A lens has a power of +2.0 diopters. Which of the following statements is correct about the lens?

  1. AThe lens is concave and its focal length is 0.5 m.
  2. BThe lens is convex and has a focal length of 2.0 m.
  3. CThe lens is convex and its focal length is 0.5 m.
  4. DThe lens is concave and its focal length is 2.0 m.
Show answer & explanation

Answer: C) The lens is convex and its focal length is 0.5 m.

Q188. What causes the twinkling of stars?

  1. Adue to the specific frequencies of starlight
  2. Bdue to reflection of starlight from the ocean surface
  3. CDue to atmospheric refraction of starlight
  4. Ddue to the Earth's magnetic field
Show answer & explanation

Answer: C) Due to atmospheric refraction of starlight

Q189. A lemon kept in a glass of water appears larger than its actual size, why does this happen?

  1. Areflection of light
  2. Bscattering of light
  3. Crefraction of light
  4. Dpolarization of light
Show answer & explanation

Answer: C) refraction of light

Q190. Mirage is an illustration of which of the following?

  1. Aonly the dispersion of light
  2. Brefraction of light only
  3. Conly total internal reflection of light
  4. DBoth refraction and total internal reflection of light
Show answer & explanation

Answer: D) Both refraction and total internal reflection of light

Q191. The Sun appears red at sunrise and sunset. What is the phenomenon in optics called that is responsible for the Sun appearing this way?

  1. Areflection
  2. Btotal internal reflection
  3. Cscattering
  4. Dinterference
Show answer & explanation

Answer: C) scattering

Q192. glass prism splits white light into different colours, this phenomenon is called dispersion of light by a prism, which of the following statements is correct?

  1. ARed light will deviate the most due to reflection of light.
  2. BDue to refraction of light, violet light will deviate the most.
  3. CDue to refraction of light, red light will deviate the most.
  4. DViolet light will deviate the most due to reflection of light.
Show answer & explanation

Answer: B) Due to refraction of light, violet light will deviate the most.

Q193. Which of the following phenomena verifies the fact that light travels much faster than sound?

  1. Atwinkling stars in the night sky
  2. Bburning of a matchstick
  3. Cthunderstorm
  4. Dmirage
Show answer & explanation

Answer: C) thunderstorm

Q194. Which of the following colours can be obtained by mixing green and red colours?

  1. ABlue
  2. BMagenta
  3. Cpink
  4. DYellow
Show answer & explanation

Answer: D) Yellow

Q195. Which of the following are the primary colours of light?

  1. AYellow, red and green
  2. BBlue, red and green
  3. CPurple, red and yellow
  4. DPurple, violet and green
Show answer & explanation

Answer: B) Blue, red and green

Q196. When light is scattered by a molecule and the frequency of the scattered light changes, what is this phenomenon called?

  1. ARayleigh scattering
  2. BRaman effect
  3. Cphotoelectric effect
  4. DRutherford scattering
Show answer & explanation

Answer: B) Raman effect

Q197. Light enters the eye through a thin membrane, what is this membrane called?

  1. Aretina
  2. Bcornea
  3. Cpupil
  4. DIris
Show answer & explanation

Answer: D) Iris

Q198. Which one of the following is not correct about the image formed by a plane mirror?

  1. AIts shape is the same as that of the object used.
  2. BIt is laterally inverted
  3. CIt is a real mirror image
  4. DIt is formed at the same distance behind the mirror as the object is in front of the mirror.
Show answer & explanation

Answer: A) Its shape is the same as that of the object used.

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