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प्रश्न
A ray of light passes through a prism of refractive index `sqrt2` as shown in the figure. Find:
- The angle of incidence (∠r2) at face AC.
- The angle of minimum deviation for this prism.
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उत्तर
(i) Since at point N, the angle of refraction is 90°, then ∠r2 is the critical angle for the glass-air pair of media.
sin ∠r2 = `1/μ = 1/sqrt2`
∴ ∠r2 = `sin^-1(1/sqrt2)` = 45°
(ii) μ = `sin(("A" + δ_"m")/2)/(sin "A"/2)`
Or, `sqrt2 = sin ((60^circ + δ_"m")/2)/(sin 60^circ/2)`
Or, `sqrt2 = sin (30^circ + δ_"m"/2)/(1/2)`
Or, 0.7 = `sin(30^circ + δ_"m"/2)`
Or, sin−1 0.7 = `30^circ + δ_"m"/2`
Or, 44.4° = `30^circ + δ_"m"/2`
∴ δm = 28.8°
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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.
State two conditions necessary for total internal reflection to occur.
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.
Total internal reflection can take place only if ______.
(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?
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
What is meant by the term ‘critical angle’?
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°.
Answer the following question.
Why is prism binoculars preferred over traditional binoculars? Describe its working in brief.
Solve Numerical example.
From the given data set, determine angular dispersion by the prism and dispersive power of its material for extreme colours. nR = 1.62 nV = 1.66, δR = 3.1°
