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प्रश्न
Name two factors which affect the critical angle for a given pair of media. State how do the factors affect it.
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उत्तर
The factors which affect the critical angle are:
- Wavelength (colour) of light: Since a transparent medium's refractive index increases with violet light and decreases with red light, the critical angle for a pair of media increases with red light and decreases with violet light. Thus, the critical angle rises as the light's wavelength increases.
- The temperature: The critical angle for that pair of media increases as the temperature of the medium rises because its refractive index falls. As a result, the critical angle rises as the temperature rises.
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संबंधित प्रश्न
State the relation between the critical angle and the absolute refractive index of a medium.
What is total internal reflection?
Swarali has got the following observations while doing an experiment. Answer her questions with the help of observations.
Swarali observed that the light bent away from the normal, while travelling from dense medium to rarer medium. When Swarali increased the values of angle of incidence (i), the values of angle of refraction (r) went on increasing. But at a certain angle of incidence, the light rays returned into the dense medium.
So, Swarali has some questions. Answer them –
a) Name this certain value of ‘i ’. What is the value of ‘r’ at that time ?
b) Name this process of returning of light in dense medium. Explain the process.
(i) Define critical angle.
(ii) State one important factor which affects the critical angle of a given medium.
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].
In the following figure, show two rays A and B travelling from water to air. If the critical angle for water- air surface is 48°, complete the ray diagram showing the refracted rays for each. State conditions when the ray will suffer total internal reflection.
Choose the correct option.
Select the WRONG statement.
Which of the following is not involved in formation of a rainbow?
The diagram below shows a fish in the tank and its image seen on the surface of the water.
Name the phenomenon responsible for the formation of this image.
State two differences between normal reflection and total internal reflection.
