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प्रश्न
Answer the following question.
Under what conditions are total internal reflection possible? Explain it with a suitable example.
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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.
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संबंधित प्रश्न
Which colour of light has a higher critical angle? Red light or green light.
What do you understand by the deviation produced by a prism? Why is it caused?
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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.
One day Chetan’s mother developed a severe stomach ache all of a sudden. She was rushed to the doctor who suggested for an immediate endoscopy test and gave an estimate of expenditure for the same. Chetan immediately contacted his class teacher and shared the information with her. The class teacher arranged for the money and rushed to the hospital. On realizing that Chetan belonged to a below average income group family, even the doctor offered concession for the test fee. The test was conducted successfully.
Answer the following questions based on the above information:
(a) Which principle in optics is made use of in endoscopy?
(b) Briefly explain the values reflected in the action taken by the teacher.
(c) In what way do you appreciate the response of the doctor on the given situation?
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(b) Draw diagram of a prism periscope.
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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?
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A ray of light is incident on a glass surface at an angle of 50° with the corresponding angle of refraction 30°. Find the value of the R.I. of glass.
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?
Choose the correct option.
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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?
Observe the given figure and write appropriate phenomenon of light in the box.
For a ray of light, the critical angle is minimum when it travels from ______.
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Optical Fibres are based on the phenomenon of dispersion.
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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.
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A ray of light passes from vacuum into a medium of refractive index µ, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is ______.
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 ______.
Small air bubbles rising up a fish tank appear silvery when viewed from some particular angle is due to the ______.
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