Advertisements
Advertisements
Question
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°
Advertisements
Solution
Given: nR = 1.62, nV = 1.66, δR = 3.1°
To find: i. Angular dispersion (δVR)
ii. Dispersive power (ωVR)
Formula: i. δ = A (n − 1)
ii. δVR = δV − δR
iii. ω = `(δ_"V"-δ_"R")/(((δ_"V"+δ_"R")/2))`
Calculation: From formula (i),
δR = A(nR − 1)
∴ A = `δ_"R"/(("n"_"R"-1))=3.1/((1.62-1))=3.1/0.62`
∴ δV = A(nV − 1) = 5 × (1.66 − 1) = 3.3°
From formula (ii),
δVR = 3.3 − 3.1 = 0.2°
From formula (iii),
ωVR = `(3.3-3.1)/(((3.3+3.1)/2))=0.2/6.4xx2=0.2/3.2=1/16`
= 0.0625
- Angular dispersion by prism is 0.2°
- Dispersive power of material of prism is 0.0625.
APPEARS IN
RELATED QUESTIONS
You are given prisms made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prisms which will
(a) deviate a pencil of white light without much dispersion,
(b) disperse (and displace) a pencil of white light without much deviation.
Name the factors affecting the critical angle for the pair of media.
State the relation between the critical angle and the absolute refractive index of a medium.
Draw the diagram of a right-angled isosceles prism which is used to make an invented image erect.
A light ray does not bend at the boundary in passing from one medium to the other medium if the angle of incident is ______.
What is total internal reflection?
Total internal reflection occurs only when a ray of light passes from a ______ medium to a ______ medium.
In the given figure PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS.
- State the special name given to the angle of incidence ∠PQN of the ray PQ.
- What is the angle of refraction for the refracted ray QS?
- Name the phenomenon that occurs if the angle of incidence ∠PQN is increased.
- The ray PR suffers partial reflection and refraction on the water-air surface. Give reason.
- Draw in the diagram the refracted ray for the incident ray PR and hence show the position of image of the object P by the letter P’ when seen vertically from above.
Two isosceles right-angle glass prisms P and Q are placed near each other as shown in Fig. Complete the path of the light ray entering the prism P till it emerges out of the prism Q.
Calculate the speed of light in a medium whose critical angle is 30° ?
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.
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?
If a ray of light passes from medium I to medium II without any change of direction, what can be said about the refractive indices of these media (angle I is not 0)?
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?
Answer the following question.
Why is prism binoculars preferred over traditional binoculars? Describe its working in brief.
Solve Numerical example.
A monochromatic ray of light is incident at 37° on an equilateral prism of refractive index 3/2. Determine angle of emergence and angle of deviation. If angle of prism is adjustable, what should its value be for emergent rays to be just possible for the same angle of incidence?
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]
For total internal reflection to take place, the angle of inddence i and the refractive index µ of the medium must satisfy the inequality ____________.
Optical fibre communication uses the principle of ______.
The twinkling effect of star light is due to ______.
A bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
What is the phenomenon used in optical fiber? Explain.
Observe the given figure of the raindrop and answer the following questions:
- Label A and B of the given diagram. Why colour will deviate most.
- Name the phenomenon shown in label C.
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 ______.
