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प्रश्न
Why do we get a spectrum of seven colors when white light is dispersed by a prism?
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उत्तर
The refractive index of the material of the prism is different for different colours. White light is composed of seven colours. When white light is incident on a prism, the constituent colours get refracted through different angles and get dispersed. So, the rays of each colour emerge along different paths and become distinct. Hence, we get a spectrum of seven different colours.
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संबंधित प्रश्न
Explain the term absolute refractive index of a medium and write an expression to relate it with the speed of light in vacuum.
State the dependence of angle of deviation On the refractive index of the material of the prism.
Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.
Light passes through a rectangular glass slab and through a triangular glass prism. In what way does the direction of the two emergent beams differ and why?
Draw the diagram of refraction of light in the glass slab
The following diagram shows a 60°, 30°, 90° glass prism of critical angle 42°, Copy the diagram and complete the path of incident ray AB emerging out of the prism marking the angle of incidence on each surface.
How can you bend light away from the normal?
Draw diagrams to show the refraction of light from
- air to glass, and
- glass to air. In each diagram, label the incident ray, refracted ray, the angle of incidence
- and the angle of refraction (r).
A ray of light strikes the surface of a rectangular glass block such that the angle of incidence in
air is 0°.
In each case, draw diagram to show the path taken by the ray as it passes through the glass block and emerges from it.
Fill in the blanks to complete the following sentence
The refractive index of glass with respect to air is 3/2. The refractive index of air with respect to glass will be ……………….
How is the angle of emergence related to the angle of incidence when prism is in the position of minimum deviation? Illustrate your answer with help of a labelled diagram using an equilateral prism?
A Water pond appears to be 2.7 m deep. If the refractive index of water is 4/3, find the actual depth of the pond.
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.
What is meant by the statement the critical angle for diamond is 24°?
The refractive index of air with respect to glass is expressed as `""_g μ_a=sin i /sin r`.
- Write down a similar expression for aμg in terms of the angles i and r.
- If angle r = 90°, what is the corresponding angle i called?
- What is the physical significance of the angle i in part (b)?
A ray of light OP passes through a right angles prism as shown in the adjacent diagram.
(a) State the angles of incidence at the faces AC and BC.
(b) Name the phenomenon which the ray suffers at the face AC.
Which of the following is the best experimental set-up out of the four shown for tracing the path of a ray of light passing through a rectangular glass slab ?
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 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
Which of the following has the highest refractive index:
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.
A ray of light strikes the surface at a rectangular glass slab such that the angle of incidence is 45o.
In each case, draw diagram to show the path taken by the ray as it passes through the glass slab and emerges from it.
Using the curve, how do you infer that for given prism, the angle of minimum deviation δmin is unique for the given light?
How does the deviation produced by a prism depend on the refraction index of its material.
Glass is transparent in nature. Why does glass powder look opaque? When water is poured over it, it again becomes transparent. Why?
A fish swimming in a pond seems nearer than it really is. Explain.
Name the material for which the refractive index is found to be maximum.
The refractive index of air with respect to glass is defined: as gµa = sin i/sin r
Write down a similar expression for aµg in terms of angle i and r.
A ray of monochromatic light is incident from air into a glass slab. Draw a labelled ray diagram indicating the change in its path till it emerges out of the slab. In the diagram, mark the angle of incidence (i) and the angle of refraction (r) at the first interface. How is the refractive index of glass related to the angles i and r?
Complete the ray diagram showing its emergence into the air after passing through the prism.
How will you verify the laws of refraction or how the refractive index of glass is determined in the laboratory?
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
What is the angular, deviation of the emergent ray from the glass block with respect to the incident ray?
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).
Explain with the help of a diagram of how fish is able to see the objects above it.
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.
