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प्रश्न
State two conditions necessary for total internal reflection to occur.
Write the two conditions for total internal reflection of light.
State the conditions required for total internal reflection of light to take place.
State the two conditions under which total internal reflection occurs.
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उत्तर
- The light must travel from a denser medium to a rarer medium.
- The angle of incidence must be greater than the critical angle for the pair of media.
Notes
Students should refer to the answer according to their questions.
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संबंधित प्रश्न
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
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.
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.
Plot a graph between
Sine of angle of incidence versus sine of angle of refraction,
If a light ray does not undergo, refraction at the boundary between two media, the angle of incidence is:
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.
How does a ray of light bend when it travels from when it is normal to the interface of the two media.
Why do diamonds sparkle?
Write down the relationship between the critical angle and the refractive index of the medium.
How are critical angles related to the refractive index of the medium?
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
State one factor on which a critical angle for a given pair of media depends. The critical angle for the glass-air interface is 45° for the yellow light. Will it be equal to, less than or greater than 45° for (i) red light, (ii) blue light?
What is meant by the statement, ‘the critical angle for diamond is 24°’?
How is the critical angle of a material related to its refractive index?
What is meant by the term ‘critical angle’?
PQ and PR are two light rays emerging from the object as shown in the figure below:
(i) What is the special name given to the angle of incidence (∠PQN) of ray PQ?
(ii) Copy the ray diagram and complete it to show the position of the image of the object P when seen obliquely from above.
(iii) Name the phenomenon that occurs if the angle of incidence ∠PQN is increased still further.
Choose the correct option.
Consider the following phenomena/ applications: P) Mirage, Q) rainbow, R) Optical fibre and S) glittering of a diamond. Total internal reflection is involved in
Choose the correct option.
Angles of deviation for extreme colours are given for different prisms. Select the one having maximum dispersive power of its material.
Answer the following question.
Under what conditions are total internal reflection possible? Explain it with a suitable example.
Describe the construction and working of an optical fibre.
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
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 ______.
Total internal reflection can take place only if light is travelling from ______.
The phenomena involved in the reflection of radiowaves by ionosphere is similar to ______.
A jar of height h is filled with a transparent liquid of refractive index µ (Figure). At the centre of the jar on the bottom surface is a dot. Find the minimum diameter of a disc, such that when placed on the top surface symmetrically about the centre, the dot is invisible.
A given ray of light suffers minimum deviation in an equilateral prism P. Additional prism Q and R of identical shape and of the same material as P are now added as shown in the figure. The ray will now suffer ______.
When a ray of light is refracted from one medium to another, then the wavelength changes from 6000 Å to 4000 Å. The critical angle for the interface will be ______.
