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There are three optical media, 1,2 and 3 with their refractive indices $μ_{1} > μ_{2} > μ_{3} .$ (TIR-total internal reflection)

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Important Questions on Ray Optics and Optical Instruments

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A monochromatic light is incident from air on a refracting surface of a prism of angle

75^{o}

and refractive index

n_{0} = \sqrt{3} .

The other refracting surface of a prism is coated by a thin film of material of refractive index

n

as shown in figure. The light suffers total internal reflection at the coated prism surface for an incidence angle of

θ \leq 60^{o} .

The value of

n^{2}

is_______.

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A ray of light is incident from a denser to a rarer medium. The critical angle for total internal reflection is

θ_{iC}

and Brewster's angle of incidence is

θ_{iB}

, such that

\frac{sin θ_{iC}}{sin θ_{iB}} = η = 1.28

. The relative refractive index of the two media is

EASY

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

In total internal reflection, when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction?

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

The critical angle for light going from medium

x

to medium

y

θ

. The speed of light in medium

x

v_{x}

. The speed of light in medium

y

HARD

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A ray of light incident parallel to the base

P Q

of an isosceles right - angled triangular prism

P Q R

suffers two successive total internal reflections at the face

P Q

and

Q R

before emerging reversed in direction as shown.
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If the refractive index of the prism is

μ

, then

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A transparent cube of side

d

, made of a material of refractive index

μ_{2}

, is immersed in a liquid of refractive index

μ_{1} (μ_{1} < μ_{2})

. A ray is incident on the face

A B

at an angle

θ

(shown in the figure). Total internal reflection takes place at the point

E

on the face

B C .

Then,

θ

must satisfy

HARD

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A point source S is placed at the bottom of a transparent block of height 10 mm and refractive index 2.72. It is immersed in a lower refractive index liquid as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm on the top of the block. The refractive index of the liquid is

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EASY

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

State one important factor which affects the critical angle of a given medium.

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A ray of light originates from inside a glass slab and is incident on its inner surface at an angle $θ$ as shown,

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In this experiment the location $x$ of the spot where they ray hits the screen is recorded. Which of the following correctly shown the plot of variation of $x$ with the angle $θ$ ?

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HARD

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A ray of light incident on a glass sphere (refractive index

\sqrt{3}

) suffer total internal reflection before emerging out exactly parallel to the incident ray. The angle of incidence was

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

The critical angle of a medium for a specific wavelength, if the medium has relative permittivity

3

and relative permeability

\frac{4}{3}

for this wavelength, will be:

HARD

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

An isosceles glass prism with base angles

40 °

is champed over a tray of water in a position such that the base is just dipped in water. A ray of light incident normally on the inclined face suffers total internal reflection at the base. If the refractive index of water is

1.33

then the condition imposed on the refractive index,

μ

of the glass is-

EASY

Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

There is a small source of light at some depth below the surface of water (refractive index

= \frac{4}{3}

) in a tank of large cross sectional surface area. Neglecting any reflection from the bottom and absorption by water, percentage of light that emerges out of surface is (nearly):
[Use the fact that surface area of a spherical cap of height

h

and radius of curvature

r

2 π r h

]

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are

1.39

1.44

and

1.47

respectively.

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The prism will:

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Physics>Optics>Ray Optics and Optical Instruments>Total Internal Reflection and Critical Angle

The diagram below shows a light source P embedded in a rectangular glass block ABCD of critical angle 42°. Complete the path of the ray PQ till it emerges out of the block. Write necessary angles.

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