(b) For two media, a and b prove that a n b = refractive index . of the medium b refractive index of the medium a .

The Snell's law simply relates angles i and r to the refraction indices of the two media A and B . Therefore, refractive index of medium B relative to medium A is sin i sin r = n 1 n 2 = n b a ∴ n b a = = refractive index . of the medium b refractive index of the medium a .

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 that the incident and the emergent rays are parallel to each other when the ray passes through a parallel-sided block. What will be the lateral shift of the ray?

Important Questions on Refraction of Light

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 1

(b) For two media, a and b prove that

_{a} n^{b}

= \frac{refractive index . of the medium b}{refractive index of the medium a} .

MEDIUM

12th West Bengal Board

IMPORTANT

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

There is some liquid in a pot. Establish the relation between real depth, and the apparent depth of the liquid when viewed normally from above. How will the apparent depth change when viewed slantingly?

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 3

An object is viewed through a parallel-sided glass plate. If d be the thickness of the plate and n the r.i. of glass, then prove that the apparent displacement of the object towards the observer

= (n - 1) \frac{d}{n}

Also prove that the apparent displacement of the object is independent of its position below the glass plate.

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 13 - Refraction of Light>EXERCISE 13>Q 4

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.

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?

Prove that the incident and the emergent rays are parallel to each other when the ray passes through a parallel-sided block. What will be the lateral shift of the ray?

Important Questions on Refraction of Light

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