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प्रश्न
(i) Define critical angle.
(ii) State one important factor which affects the critical angle of a given medium.
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उत्तर
(i) The angle of incidence for which the angle of refraction is 90o is called critical angle.
`"_1 mu _2 = (sin i_c)/(sin (90^circ))`
`therefore (mu_2)/(mu_1) = (sini_c)/(1)`
` therefore 1/mu = sini_c " If " mu_2 = 1 mu_1 = mu`
` therefore i_c = sin^(-1) (1/mu)`
(ii) Relative refractive of the medium `("_1 mu_2)`1
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संबंधित प्रश्न
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.
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].
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
What is meant by the statement, ‘the critical angle for diamond is 24°’?
A ray of light is incident as a normal ray on the surface of separation of two different mediums. What is the value of the angle of incidence in this case?
A spherical marble, of refractive index 1.5 and curvature 1.5 cm, contains a tiny air bubble at its centre. Where will it appear when seen from outside?
What are the conditions to achieve total internal reflection?
A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5° and the prism is made of a material of refractive index 1.5, the angle of incidence is ______.
- Assertion (A): Propagation of light through an optical fibre is due to total internal reflection taking place at the core-cladding interface.
- Reason (R): Refractive index of the material of the cladding of the optical fibre is greater than that of the core.
