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प्रश्न
Answer the following question.
Define the critical angle of incidence and obtain an expression for it.
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उत्तर
- The critical angle for a pair of refracting media can be defined as that angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90°.
- Let n be the relative refractive index of a denser medium with respect to the rarer.
- Then, according to Snell’s law,
n = `"n"_"denser"/"n"_"rarer"=(sin"r")/(sin"i"_"c")=(sin90°)/(sin"i"_"c")`
∴ sin (ic) = `1/"n"`
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संबंधित प्रश्न
Draw the diagram of a right-angled isosceles prism which is used to make an invented image erect.
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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:
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- Reason (R): Refractive index of the material of the cladding of the optical fibre is greater than that of the core.
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