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प्रश्न
What is total internal reflection?
Explain total internal reflection of light.
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उत्तर
Total internal reflection is the phenomenon when a ray of light travelling in a denser medium is incident at the surface of a rarer medium such that the angle of incidence is greater than the critical angle for the pair of media, and the ray is totally reflected back into the denser medium.
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संबंधित प्रश्न
The diagram below shows a point source P inside a water container. Four rays A, B, C, D starting from the source P are shown up to the water surface
1) Show in the diagram the path of these rays after striking the water surface.
The Critical Angle for the water-air surface is 48°.
2) Name the phenomenon which the rays B and D exhibit.
Angle of deviation is the angle which the ______ ray makes with the direction of ______ray.
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.
Define critical angle for a given medium.
The diagram shows a point source P inside a water container. Three rays A, B, and C starting from P are shown up to the water surface. Show in the diagram the path of these rays after striking the water surface. The critical angle for the water-air pair is 48°.
Complete the following diagram to show the path of the ray of a single colour in the diagram as if enters in and emerges out of the prism. Mark the angles wherever necessary. (Critical angle for glass = 42°).
A ray of light is incident on a glass surface at an angle of 50° with the corresponding angle of refraction 30°. Find the value of the R.I. of glass.
For the same angle of incidence, the angle of refraction in four media A, B, C and D are 25°, 30°, 35° and 40° respectively. The speed of light is least in medium ______.
For a ray of light, the critical angle is minimum when it travels from ______.
Optical fibre communication uses the principle of ______.
The entire light is reflected back into the denser medium is called ______.
The angle of incidence at which the angle of refraction is Q£ is called the critical angle.
What is the phenomenon used in optical fiber? Explain.
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Figure). When observed from the face AD, the pin shall ______.
- appear to be near A.
- appear to be near D.
- appear to be at the centre of AD.
- not be seen at all.
A Rainbow is a beautiful natural phenomenon formed because of the following:
Which of the following is used in optical fibres?
Find the value of θ in the given figure.
Name any two phenomena which take place in the formation of a rainbow.
