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    Refraction of Light

    Uploaded by

    Asish Thampi
    This document contains 9 questions and answers about refraction of light. It discusses key concepts like total internal reflection, image formation using convex lenses, refractive index, and speed of light in different media. The questions cover how refraction causes the angle of refraction to be less than the angle of incidence, how to calculate focal length and refractive index, and arranging media by optical density.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Refraction of Light

    Uploaded by

    Asish Thampi
    191 views4 pages
    This document contains 9 questions and answers about refraction of light. It discusses key concepts like total internal reflection, image formation using convex lenses, refractive index, and speed of light in different media. The questions cover how refraction causes the angle of refraction to be less than the angle of incidence, how to calculate focal length and refractive index, and arranging media by optical density.

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    Original Title

    5. Refraction of light

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    This document contains 9 questions and answers about refraction of light. It discusses key concepts like total internal reflection, image formation using convex lenses, refractive index, and speed of light in different media. The questions cover how refraction causes the angle of refraction to be less than the angle of incidence, how to calculate focal length and refractive index, and arranging media by optical density.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    191 views4 pages

    Refraction of Light

    Uploaded by

    Asish Thampi
    This document contains 9 questions and answers about refraction of light. It discusses key concepts like total internal reflection, image formation using convex lenses, refractive index, and speed of light in different media. The questions cover how refraction causes the angle of refraction to be less than the angle of incidence, how to calculate focal length and refractive index, and arranging media by optical density.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 4

    CHAPTER 5

    REFRACTION OF LIGHT
    Previous Exam Questions and Answers

    1. Which phenomenon of light is utilised in optical fibre


    technology? (Refraction, Total internal reflection, Dispersion,
    Scattering)
    Total internal reflection
    2. The image formed by a convex lens is inverted and diminished.
    Then the object must be placed (At 2F, Beyond 2F, Between F
    and 2F, At F)
    Beyond 2F
    3. A ray of air light falling obliquely from air to a glass slab is
    shown in the figure.

    (a) Find out the angle of incidence.


    (b) Why the angle of refraction is less than that of the angle of
    incidence in this case?
    (c) How can you calculate the refractive index of the material of
    this slab? (Calculation not required)
    (a) Angle of incidence = 60°
    (b) Glass is optically denser than the air./ Glass has higher
    refractive index than the air. Hence the refracted ray bends towards
    the normal.

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    𝑆𝑖𝑛𝑖 𝑆𝑖𝑛60
    (c) Refractive index of glass = 𝑆𝑖𝑛𝑟
    = 𝑆𝑖𝑛33
    i = angle of in incidence, r = angle of refraction
    4. The radius of curvature of a convex lens is 50cm. What is its
    focal length?
    (+25cm, +50cm, -25cm, -50cm)
    Ans : +25 cm
    5. An image is obtained at a distance of 40cm away from a convex
    lens when the object placed at the same distance on the opposite
    side.
    (a) Write any two characteristics of the image obtained.
    (b) Write the focal length of the given lens.
    (a) Image is having same size of the object, inverted and real.
    𝑢𝑣 −40 × 40
    (b) f = 𝑢−𝑣
    = −40 − 40
    = + 20 cm

    6. Speed of light in three media are given.


    (Glass - 2 x 108 m/s, Water - 2.25 x 10 8 mis, Diamond 1.25 x 108
    m/s)
    (a) In which medium does the refraction of light occurs more
    while falling from air?
    (b) Arrange the three given media in the increasing order of
    optical density.
    (a) Diamond
    (b) Water < Glass < Diamond
    7. Draw the ray diagram of image formation when an object is
    placed at the 2F of a convex lens.

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    8. Observe the figure.

    (a) Write the values of u and f by using Cartesian sign


    convention.
    (b) Calculate the distance of the image from the lens.
    (a) u = - 45cm, f = - 30cm
    1 1 1 𝑢𝑓 −45 × −30
    (b) 𝑓
    = 𝑣
    - 𝑢
    ,v= 𝑢+𝑓
    = −45 + −30
    = -18 cm

    9. Speed of light in certain media are given in the table given below.
    Analyse the table and answer the following questions.

    Media Speed of light (m/s)


    vacuum 3 X 108
    Water 2.25 X 108
    Diamond 1.25 X 108
    Glass 2 X 108

    (a) Rearrange the given media in the increasing order of their


    optical density.
    (b) If light enters obliquely making the same angle of incidence
    from air to these media separately, which media will give the
    largest value of the angle of refraction?
    (c) What do you mean by absolute refractive index?
    Calculate the absolute refractive index of glass from the given
    data.
    Ans: (a) Vacuum, water, glass, diamond
    (b) Water
    (c) If the refractive index of a medium with respect to vacuum is

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    called absolute refractive index.
    8
    3 × 10
    Absolute refractive index = 8
    = 1.5
    2 × 10

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