Ray Optics & Optical Instruments  MCQs

MCQs of Ray Optics & Optical Instruments

Showing 11 to 20 out of 143 Questions
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11.
If the tube length of astronomical telescope is 105 cm and magnifying power is 20 for normal setting, then the focal length of the objective is _____ cm.
(a) 10
(b) 20
(c) 25
(d) 100
Answer:

Option (d)

12.
The top sky looks blue in morning hours because, _____ .
(a) red light is absorbed
(b) blue light is scattered the most
(c) sun radiates blue light only in the morning.
(d) blue light is absorbed by the sky
Answer:

Option (b)

13.
A short pulse of white light is incident from air to a glass slab at normal incidence.After travelling through the slab, the first colour to emerge is_____.
(a) Blue
(b) Green
(c) Violet
(d) Red
Answer:

Option (d)

14.
Stokes and antistokes lines observed in Raman scattering is due to _____ of light.
(a) reflection
(b) elastic scattering
(c) inelastic scattering
(d) dispersion
Answer:

Option (c)

15.
A convex lens of focal length 10 cm is used as a simple microscope. When image of an object is obtained at infinite, magnification is _____ Near point for normal vision is 25 cm.
(a) 1.0
(b) 2.5
(c) 0.4
(d) 25
Answer:

Option (b)

16.
A spherical convex surface separates an object and image spaces of refractive index 1.0 and 1.5 respectively. If radius of curvature of the surface is 25 cm, its power is ______ D.
(a) 13
(b) 33
(c) 3.3
(d) 1.3
Answer:

Option (b)

17.
A light ray is incident at an angle 30° with normal on a 3 cm thick plane slab of refractive index n = 2.0. The lateral shift of the incident ray is _____ cm.
(a) 0.835
(b) 8.35
(c) 1.5
(d) 1.197
Answer:

Option (a)

18.
The focal length of an equiconvex lens in air is equal to either of its radii of curvature. The refractive index of the material of the lens is _____ .
(a) 43
(b) 1.5
(c) 2.5
(d) 0.8
Answer:

Option (b)

19.
Time taken by the sunlight to pass through a slab of thickness 4 mm and refractive index 1.5 is _____ sec.
(a) 2 × 10-8
(b) 2 × 108
(c) 2 × 10-11
(d) 2 × 1011
Answer:

Option (c)

20.
An image of an object obtained by a convex mirror is n times smaller than the object. If the focal length of lens is f, the object distance would be _____ .
(a) fn
(b) fn-1
(c) n-1f
(d) nf
Answer:

Option (c)

Showing 11 to 20 out of 143 Questions
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