A light ray is incident at an angle of 45 ° with the normal to a 2 cm thick plate ( μ = 2 ) . Find the shift in the path of the light as it emerges out of the plate.

Given, Angle of incidence = 45 ˚ Thickness of the plate = 2 cm Refractive index ( μ ) of the plate = 2 . 0 Applying Snell's law, sin i sin r = 1 μ ⇒ sin i sin r = 2 1 ⇒ sin r = sin 45 ° 2 ⇒ sin r = 1 2 2 ⇒ r = 21 ° From figure, we know that B D is the shift in path which is equal to (AB)sin 24 ˚ = 0 . 406 × A B = A E cos 21 ° × 0 . 406 = 0 . 62 c m

MEDIUM

12th West Bengal Board

IMPORTANT

Earn 100

Prove with a neat ray-diagram how after refraction of light from the two opposite plane faces of a rectangular glass slab, the resultant deviation of the emergent ray from the incident ray becomes zero and mark in the diagram the lateral displacement.

Important Questions on Refraction of Light

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 5

A light ray is incident at an angle of

45 °

with the normal to a

\sqrt{2} cm

thick plate

(μ = 2) .

Find the shift in the path of the light as it emerges out of the plate.

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 6

Clearly explain 'total internal reflection' and 'critical angle'. What is the relation between the critical angle and the refractive index of the denser medium?

State whether critical angle is available in the following cases :-(i) rays of light are going from air to glass

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 6

Clearly explain 'total internal reflection' and 'critical angle'. What is the relation between the critical angle and the refractive index of the denser medium?

State whether critical angle is available in the following cases :- (ii) rays of light are going from glass to air.

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 7

What is a mirage? Explain, with a neat diagram, how a mirage is formed? Is it a real or a virtual image?

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 8

We, on the surface of the earth, see the sun to describe daily an arc of a circle of

180 °

in air but a fish in water will see it as an arc of a circle of

98 ° .

Explain.

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 9

What is a prism? Cite some specific uses of prisms. A ray of light is incident normally on a refracting face of a prism whose refracting angle is

60 ° .

Draw the path of the ray through the prism. Suppose, the critical angle for glass is

42 °

and that the prism has two faces.

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 10

Describe briefly the principle of operation of a totally reflecting prism.

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 11

What is the angle of deviation of a ray in connection with the refraction through a prism? Find an expression for it and explain, with a diagram, the variation of the angle of deviation with the variation of the angle of incidence.

Prove with a neat ray-diagram how after refraction of light from the two opposite plane faces of a rectangular glass slab, the resultant deviation of the emergent ray from the incident ray becomes zero and mark in the diagram the lateral displacement.

Important Questions on Refraction of Light

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