Total Internal Reflection and Its Applications

IMPORTANT

Total Internal Reflection and Its Applications: Overview

This topic covers concepts, such as, Total Internal Reflection, Critical Angle, Total Internal Reflection in Liquids, Total Internal Reflection in Optical Fibers & Total Reflecting Prisms etc.

Important Questions on Total Internal Reflection and Its Applications

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A beam of light consisting of red, green and blue and is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelength are 1.39, 1.44 and 1.47 respectively. The prism will

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MEDIUM
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A ray of light traveling in a denser medium strikes the boundary of a rarer medium and gets partially reflected and refracted. The angle of reflection is r and that of refraction is r'. If the reflected and refracted rays make an angle of 90° with each other, then the critical angle for the pair of media is

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Two glass blocks of triangular cross section(n=1.5) are used to make a periscope. Which of the following is the correct arrangement?

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A point source of light is placed at a distance h below the surface of a large deep lake. What is the percentage of light energy that escapes directly from the water surface is μ of the water = 4/3? (neglect partial reflection)

MEDIUM
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A small source of light is 4 m below the surface of a liquid of refractive index 5/3. In order to cut off all the light coming out of liquid surface, minimum diameter of the disc placed on the surface of liquid is

EASY
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In the figure ABC is the cross section of a right angled prism and BCDE is the cross section of a glass slab. the value of θ so that light incident normally on the face AB does not cross the face BC is (given sin-1 (3/5) = 37o)

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HARD
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A rod made of glass (μ=1.5) and of the square cross-section is bent into the shape shown in the figure. A parallel beam of light falls perpendicularly on the plane flat surface A. Referring to the diagram, d is the width of a side & R is the radius of the inner semicircle. Find the maximum value of ratio dR so that, all light entering the glass through surface A emerge from the glass through surface B

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HARD
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A room contains air in which the speed of sound is 340 m s-1. The walls of the room are made of concrete in which the speed of sound is 1700 m s-1. (a) Find the critical angle for total internal reflection of sound at the concrete - air boundary. (b) In which medium must the sound be travelling to undergo total internal reflection?

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An optical fibre is based on:

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A ray of light from a denser medium strikes a rarer medium at an angle of incidence i (see figure). The reflected and refracted rays make an angle of 90° with each other. The angles of reflection and refraction are  r and r'  The critical angle is

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EASY
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A glass prism of refractive index 1.5 is immersed in water (refractive index 43). A light beam incident normally on the face AB is totally reflected to reach on the face BC if

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EASY
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Light travels a distance x in time t1 in air and 10x in time t2 in another denser medium. What is the critical angle for this medium?

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A glass rod of rectangular cross-section is bent into the shape shown in the diagram. A parallel beam of light falls perpendicularly on the flat surface A. Determine the minimum value of the ratio Rd for which all light entering the glass through surface A will emerge from the glass through surface B. The index of refraction of the glass is 1.5.

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MEDIUM
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Critical angle of light passing from glass to air is minimum for:

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It is possible to observe total internal reflection,when a ray travels from :

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A ray of light travelling in a transparent medium of refractive index µ, falls on a surface separating the medium from air at an angle of incidence of 45°. For which of the following value of µ the ray can not undergo total internal reflection ?

EASY
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Light is incident normally on face AB of a prism as shown in the figure. A liquid of refractive index μ is placed on face AC to the prism. The prism is made of glass of refractive index 3/2. The limit of μ for which total internal reflection takes place on face AC is :-

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EASY
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The critical angle of light going from medium A to medium B is θ. The speed of light in medium A is v. The speed of light in medium B is :

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A right-angled isosceles prism is held on the surface of a liquid composed of miscible solvents A and B of refractive index nA=1.50 and nB=1.30, respectively. The refractive index of prism is np=1.5 and that of the liquid is given by nL=CAnA+1-CAnB, where CA is the percentage of solvent A in the liquid:-

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If θC is the critical angle at prism-liquid interface, the plot which best represents the variation of the critical angle with the percentage of solvent is:

EASY
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Which of the following is not due to total internal reflection?