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प्रश्न
(a) A ray of monochromatic light enters glass PQRS as shown in the fig. Complete the path of ray till it emerges from the glass. (Critical angle of glass is 420).
(b) Draw diagram of a prism periscope.
(c) What are the advantages of total internal reflecting prism over plane mirror?
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उत्तर
Note : here that when the angle of incidence in the denser medium is more than the critical angle (= 42), then the ray undergoes total internal reflection.
At angle of incidence equal to critical angle, the ray grazes the interface.
(b) Diagram of prism periscope:
(c) In case of reflection from plane mirror, all of light in not reflected. In case of total reflecting prism, all rays failing beyond critical angle will be totally reflected. The intensity of reflected light is equal to the intensity of incident light in case of total internal ref;lection but not in case of reflection from plane mirror.
In addition, the reflection through a thick mirror causes multiple image formation as well as lateral inversion of image.
Due to the above two reasons, the total reflecting prisms are preferred over the plane mirrors.
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संबंधित प्रश्न
Name two factors which affect the critical angle for a given pair of media. State how do the factors affect it.
Write the necessary conditions for the phenomenon of total internal reflection to
occur ?
Solve the previous problem if the paperweight is inverted at its place so that the spherical surface touches the paper.
The observation made by Swarali while doing the experiment is given below. Based on these write answers to the questions:
Swarali found that the light ray travelling from the denser medium to rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing. However, after certain value of the angle of incidence the light ray is seen to return back into the denser medium.
Questions:
- What is the specific value of∠i called?
- What is the process of reflection of incident rays into denser medium called?
- Draw the diagrams of three observations made by Swarali.
Can light be ‘piped’ like sound in a doctor’s stethoscope?
Name the factors affecting the critical angle for the pair of media.
Describe the construction and working of an optical fibre.
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
The angle of minimum deviation produced by a thin glass prism in air is 'δ'. If that prism is immersed in water, the angle of minimum deviation will be ______.
( aμg = refractive index of glass w.r.t, air aμw = refractive index of water w.r.t. air)
Find the value of θ in the given figure.
