Advertisements
Advertisements
प्रश्न
Answer the following question.
Under what conditions are total internal reflection possible? Explain it with a suitable example.
Advertisements
उत्तर
Conditions for total internal reflection:
- The light ray must travel from denser medium to rarer medium.
- The angle of incidence in the denser medium must be greater than critical angle for the given pair of media.
Total internal reflection in optical fibre:
- Consider an optical fibre made up of the core of refractive index n1 and cladding of refractive index n2 such that, n1 > n2.
- When a ray of light is incident from a core (denser medium), the refracted ray is bent away from the normal.
- At a particular angle of incidence ic in the denser medium, the corresponding angle of refraction in the rarer medium is 90°.
- For angles of incidence greater than ic, the angle of refraction becomes larger than 90° and the ray does not enter into the rarer medium at all but is reflected totally into the denser medium as shown in the figure.
APPEARS IN
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.
Which colour of light has a higher critical angle? Red light or green light.
A light ray does not bend at the boundary in passing from one medium to the other medium if the angle of incident is ______.
Draw diagram to illustrate the 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.
Write the necessary conditions for the phenomenon of total internal reflection to
occur ?
Plot a graph between
Angle of incidence versus angle of reflection,
Plot a graph between
Angle of incidence versus angle of refraction.
How does a ray of light bend when it travels from rarer to denser medium
Why do diamonds sparkle?
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
Draw a diagram, properly labelled, to illustrate the use of a total reflecting prism (a right-angled isosceles prism) to turn a ray of light through 180°. Name an instrument in which this device is used.
A ray of light passes through a right-angled prism as shown in the figure. State the angles of incidence at the faces AC and BC.
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°).
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 as a normal ray on the surface of separation of two different mediums. What is the value of the angle of incidence in this case?
A spherical marble, of refractive index 1.5 and curvature 1.5 cm, contains a tiny air bubble at its centre. Where will it appear when seen from outside?
Choose the correct option.
Select the WRONG statement.
Explain ‘mirage’ as an illustration of refraction.
Answer the following question.
Define the critical angle of incidence and obtain an expression for it.
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°
A green light is incident from the water to the air-water interface at the critical angle (C). Select the correct statement.
The twinkling effect of star light is due to ______.
The outer concentric shell in optic fiber is called ______.
What are the conditions to achieve total internal reflection?
Write any two uses of total internal reflection.
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:
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.
A light is entering from one medium refractive index `("RI" =5/3)` to another medium at an angle 30°. The angle of refraction for other medium is sin-1 `(5/6)`. then the increase in angle of incidence is ______ such that the ray of light reflected back into the same medium.
Find the value of θ in the given figure.
An endoscope uses optic fiber to transmit high resolution images of internal organs without loss of information. The principle of light that is used by the optic fiber is based on ______.
