Optics MCQs
1. Calculate the velocity of the light ray in the medium, if the critical angle for TIR from medium to the vacuum is 30°.
(a) 2 x 108 m/s
(b) 1.5 x 108 m/s
(c) 0.75 x 108 m/s
(d) 3 x 108 m/s
Answer: (b) 1.5 x 108 m/s
2. Which of the following is the combination that is used in the formation of achromatic lenses?
(a) 1 convex and 1 plane mirror
(b) 2 convex lenses
(c) 1 convex and 1 concave lens
(d) 2 concave lenses
Answer: (c) 1 convex and 1 concave lens
3. How does magnifying power change for an objective lens if the focal length of the objective lens is increased?
(a) The microscope will decrease but for the telescope, it will increase
(b) The microscope will increase but for the telescope, it decreases
(c) The microscope and telescope will increase
(d) The microscope and telescope will decrease
Answer: (a) The microscope will decrease but for the telescope, it will increase
4. What is the magnification produced by the plane mirror?
(a) Zero
(b) +1
(c) -1
(d) Between 0 and +∞
Answer: (b) +1
5. What happens to the refractive index on heating the liquid?(a) Increases
(b) Decreases
(c) Remains unchanged
(d) Increases or decreases depending on the rate of heating
Answer: (b) Decreases
6. Calculate the speed of light in water if the refractive index of water is 1.33(a) 4 x 108 m/s
(b) 2.25 x 108 m/s
(c) 1.33 x 108 m/s
(d) 3 x 108 m/s
Answer: (b) 2.25 x 108 m/s
7. What is hypermetropia?
(a) Bad vision due to age
(b) Short-sightedness
(c) Long-sightedness
(d) Formation of a layer on the eye
Answer: (c) Long-sightedness
8. Rainbow is an example of which phenomenon?
(a) Refraction and scattering
(b) Refraction and total internal reflection
(c) Dispersion and reflection
(d) Dispersion and total internal reflection
Answer: (d) Dispersion and total internal reflection
