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प्रश्न
Observe the following figure and answer the questions given under it:
1) How many times does refraction take place in the above figure?
2) What happens to the ray of light when it passes from air to glass?
3) What happens to the ray of light when it passes from glass to air?
4) What are the rays AB and CD in the figure called?
5) Define refraction.
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उत्तर
An expression for heat produced in a conductor by using Joule's experiment:
1) Refraction occurs twice, once at Point N and the second time at Point M.
2) Air is rarer than glass. So, when light passes from the rarer medium to the denser medium, it bends towards the normal.
3) When light passes from the denser (glass) medium to the rarer (air) medium, it bends away from the normal.
4) Ray AB is called the incident ray, and ray CD is called the emergent ray.
5) Refraction of light is the phenomenon of change in the direction of propagation of light when it passes obliquely from one transparent medium to another.
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संबंधित प्रश्न
Four students P, Q, R and S traced the path of a ray of light passing through a glass slab for an angle of incidence 40° and measured the angle of refraction. The values as measured them were 18°; 22°; 25° and 30° respectively. The student who has performed the experiment methodically is
(A) P
(B) Q
(C) R
(D) S
State the dependence of angle of deviation On the wavelength of light
Draw the diagram given below and clearly show the path taken by the emergent ray.
Which colour of light travels fastest in any medium except air?
Fill in the blanks to complete the following sentence
When light travels from a denser to a rarer medium, its speed ……………….
An object is viewed through a glass prism with its vertex pointing upwards. It appears to be displaced upward. Explain the reason.
Complete Fig. 4.32 to show the path of the ray of single colour as it enters the prism and emerges out of it. Mark the angles wherever necessary.
A postage stamp kept below a rectangular glass block of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass slab.
The critical angle for glass-air is 45° for the light of yellow colour. State whether it will be less than, equal to, or more than 45° for (i) ref light, (ii) blue light?
The refractive index of glass is 1.5. From a point P inside a glass block, draw rays PA, PB and PC incident on the glass air surface at an angle of incidence 30°, 42° and 60° respectively.
- In the diagram show the approximate direction of these rays as they emerge out of the block.
- What is the angle of refraction for the ray PB?
`("Take" sin 42° =2/3)`
Select from the following the best set-up for tracing the path of a ray of light through a rectangular glass slab:
(A) I
(B) II
(C) III
(D) IV
A ray of light falls normally on the surface of a transparent glass slab. Draw a ray diagram to show its path and also mark angle of incidence and angle of emergence.
A student traces the path of a ray of white light through a rectangular glass slab and marks, the angles of incidence (∠i) , refraction (∠r) and emergence (∠e) as shown. Which angle or angles has he not marked correctly?
(A) ∠i only
(B) ∠i and ∠r
(C) ∠i and ∠e
(D) ∠r and ∠e
Observe the figure and write accurate conclusion regarding refraction of light.
Define the term refractive index of a medium. What do you understand by the statement 'the refractive index of glass is 1.5 for white light'?
Fill in the blank to complete the following sentence:
When light travels from a rarer to a denser medium, it bends ...........
Draw an í- `delta` graph for a mono chromatic raY through a glass prism of a plane and mark
(i) `delta` m, the angle of mínimum devíation
(íí) Any two values of i for which value of `delta` ís same.
Draw a diagram to show the splitting of white light into its constituent colours.
Using the curve, how do you infer that for given prism, the angle of minimum deviation δmin is unique for the given light?
The critical angle for glass-air interface is :
Name the phenomenon responsible in the following case:
Apparent bending of a stick in water
Why do the faces of persons sitting around campfire appear to shimmer?
Why does a fisherman aim at the tail of fish during spearfishing?
A ray of light passes from water to air. How does the speed of light change?
A glass slab is placed over a page on which the word VIBGYOR is printed with each letter in its corresponding colour.
- Will the image of all the letters be in the same place?
- If not, the state which letter will be raised to the maximum. Give a reason for your answer.
Comment on the statement ‘The refractive index of glass is 3/2.’
How is the refractive index of a medium related to its real depth and apparent depth?
Explain briefly what causes the twinkling of stars at night.
Can the absolute refractive index of a medium be less than one?
The refractive index of air with respect to glass is defined: as gµa = sin i/sin r
If r = 90°, what is the corresponding angle i called?
In the diagram below, PQ is a ray of light incident on a rectangular glass block.
Copy the diagram and complete the path of the ray of light through the glass block. In your diagram, mark the angle of incidence by letter ‘i’ and the angle of emergence by the letter ‘e’.
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
(a) Does the light speed up or slow down in the glass,
(b) Give the reason for your answer.
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
What should be the rate of the speed of light through the liquid to the speed through the glass so that there is no refraction of light at the boundaries of the glass block when the system is illuminated by the light of one colour?
Trace a ray of light incident at 30° on a surface if travelling from air to glass. What is the angle of refraction in this case? (R.I. for glass = 3/2).
The diagram below shows two parallel rays A (Orange) & B (Blue) incident from air, on air-glass boundary.
- Copy and complete the path of the rays A and B.
- How do the speeds of these rays differ in glass?
- Are the two refracted rays in glass parallel? Give a reason.
