Prism

Author:Asok Kumar Das & Chittaranjan Dasgupta
12th West Bengal Board
IMPORTANT

Important Questions on Prism

HARD
IMPORTANT

Light enters a prism of angle A at a grazing incidence to emerge at angle θ with the normal. Show that the refractive index of the material of the prism is given by

μ=1+cosA+sinθsinA212

HARD
IMPORTANT

A B and C D are surfaces of two slabs Fig. 13.75. The medium between the slabs has refractive index 2. R.I. of the slabs are 2 and 3 respectively. Find the minimum angle of incidence at Q, so that the ray is totally reflected by both slabs.

HARD
IMPORTANT

A ray of light is incident at an angle of 60° on one face of prism which has an angle of 30°. The ray emerging out of the prism makes an angle of30° with the incident ray show that the emergent ray is perpendicular to the face through which it emerges and calculate the refractive
index of the material of the lens.

HARD
IMPORTANT

The refractive of the material of a prism of refracting angle 45° is 1.6 for a certain monochromatic ray. What should be the minimum angle of incidence of this ray on the prism so that no total internal reflection takes place as the ray comes out of the prism? 

HARD
IMPORTANT

The refracting angle of a prism is 90°; If α is the angle of minimum deviation and β the angle of deviation of a ray which enters at grazing incidence, then show thatα=sin2β and cosα=μcosβ, where μ is the r . i of the prism.

HARD
IMPORTANT

The refracting angle of a prism is 30°. One of its refracting faces has a coating. A ray of light incident on the other face at an angle 45° falls on the coated surface. On reflection, the ray retraces its path. Find the refractive index of the material of the prism.

HARD
IMPORTANT

Light enters a prism of refracting angle A at grazing incidence to emerge at an angle θ with normal. Show that the refractive index of the material of prism is :
μ=1+cosA+sinθsinA212   

HARD
IMPORTANT

The refracting angle of a prism is 60° and its refractive index is 3. If the prism is used at 60° angle of incidence, what will be the deviation of the ray?

EASY
IMPORTANT

A ray of light is refracted through a prism of angle 70°. If the angle of refraction in the glass at the first face is 28°, what is the angle of incidence in the glass at the second face ? 

HARD
IMPORTANT

A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter is equal to 3/4th  of the angle of the prism. Determine the angle of deviation and the refractive index of the material of the prism.

HARD
IMPORTANT

Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of the prism. Find the angle of the prism. [cos 41° 24'=0.75]

MEDIUM
IMPORTANT

The refracting angle of a prism is 60° and the angle of minimum deviation of a ray through the prism is 40°. What is the refractive index of the material of the prism ? sin 50°=0.776

HARD
IMPORTANT

Show the nature of the i-𝛿 curve for a prism. Analyse the curve to show that for any particular value of 𝛿, the difference between the fixed values of i and e decrease with the decrease of 𝛿 and becomes zero for 𝛿 minimum.

HARD
IMPORTANT

Draw a diagram showing a ray of light incident on a thick prism, refracted through it and emergent out of it. Show that 𝛿=i+i'-A and A=r+r'.[Symbols have their usual meaning]. Show in the above diagram that for angle of incidence i or i' deviation 𝛿 remains the same.

HARD
IMPORTANT

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.

HARD
IMPORTANT

A ray OP of monochromatic light is incident on the face AB of prism ABCD near vertex B at an incident angle of 60, Fig. 13.90. If the refractive index of the material of the prism is 3, which of the following is (are) correct?

Question Image

EASY
IMPORTANT

Two beams of red and violet colours are made to pass separately through a prism (angle of the prism is 60°). In the position of minimum deviation, the angle of refraction will be 

EASY
IMPORTANT

A ray of light is incident on an equilateral glass prism placed on a horizontal table Fig 13.86. For minimum deviation which of the following is true?

Question Image

EASY
IMPORTANT

A given ray of light suffers minimum deviation in an equilateral prism P Fig. 13.82. Additional prisms Q and R of identical shape and of the same material as P and now added as shown in the figure. The ray will suffer

Question Image

HARD
IMPORTANT

A ray is incident on an equilateral prism of r.i. 2. The ray emerges from the prism with a deviation of 30°. The angle made by the ray inside the prism with the base of the prism is