Advertisements
Advertisements
प्रश्न
Answer the following question.
Define the critical angle of incidence and obtain an expression for it.
Advertisements
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"`
APPEARS IN
संबंधित प्रश्न
State the conditions required for total internal reflection of light to take place
State the relation between the critical angle and the absolute refractive index of a medium.
(i) Define critical angle.
(ii) State one important factor which affects the critical angle of a given medium.
Plot a graph between
Angle of incidence versus angle of reflection,
(a) A ray of monochromatic light enters glass PQRS as shown in the fig. Complete the path of ray till it emerges from the glass. (Critical angle of glass is 420).
(b) Draw diagram of a prism periscope.
(c) What are the advantages of total internal reflecting prism over plane mirror?
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.
Images formed by totally reflecting prisms are brighter than the image formed by ordinary reflected light, why?
Name the factors affecting the critical angle for the pair of media.
How is the critical angle of a material related to its refractive index?
What is meant by the term ‘critical angle’?
The adjacent diagram shows two right-angled isosceles prisms A and B. Complete the diagram to show the path of rays P and Q emerging out of the prism B. What principles have you used to complete the diagram?
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°).
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.
Which of the following is not involved in formation of a rainbow?
Answer the following question.
Under what conditions are total internal reflection possible? Explain it with a suitable example.
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
Answer the following question.
Why is prism binoculars preferred over traditional binoculars? Describe its working in brief.
The resultant `vec"R"` of `vec"P"` and `vec"Q"` is perpendicular to `vec"P"`. Also `|vec"P"|=|vec"R"|`. The angle between `vec"P"` and `vec"Q"` is ______.
[tan 45° = 1]
The angle of minimum deviation produced by a thin glass prism in air is 'δ'. If that prism is immersed in water, the angle of minimum deviation will be ______.
( aμg = refractive index of glass w.r.t, air aμw = refractive index of water w.r.t. air)
The entire light is reflected back into the denser medium is called ______.
What is a mirage? How does it occur?
What is the phenomenon used in optical fiber? Explain.
Write any two uses of total internal reflection.
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 ______.
The angle made by incident ray of light with normal of the reflecting surface is called ______.
State two differences between normal reflection and total internal reflection.
