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प्रश्न
Define refraction and state the laws of refraction.
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उत्तर
The phenomenon of change in the direction of propagation of light when it passes obliquely from one transparent medium to another is called refraction of light.
Laws of refraction:-
- The incident ray and the refracted ray are on the opposite sides of the normal at the point of incidence, and all three lie in the same plane.
- For a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
`sin i/sin r=mu`
This constant is called the refractive index of the second medium with respect to the first medium.
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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.
Name one factor that affects the lateral displacement of light as it passes through a rectangular glass slab.
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).
How is the refractive index of a medium related to the speed of light in it?
How does the angle of deviation produced by a prism change with increase in the angle of incidence. Draw a curve showing the variation in the angle of deviation with the angle of incidence at a prism surface.
In fig 4.18, name the ray which represents the correct path of light while emerging out through a glass block.
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 ray of light enters a glass slab ABDC as shown in figure and strikes at the centre O of the circular part AC of the slab. The critical angle of glass is 42°. Complete the path of the ray till it emerges out from the slab. Mark the angles in the diagram wherever necessary.
“A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself.” Draw labelled ray diagram to justify the statement.
Which colour of light travels fastest in any medium except air?
Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature, the glass piece is not seen.
Why is the light of a single colour used ?
How does the deviation produced by a prism depend on the refraction index of its material.
Name the phenomenon responsible in the following case:
Twinkling of stars
Name the material for which the refractive index is found to be maximum.
Can the absolute refractive index of a medium be less than one?
Why does the sun appear bigger during sunset or sunrise?
What is the total reflecting prism?
The figure shows two prisms A and B. A monochromatic ray of light PO is incident at the face of the prism A. Complete the diagram to show the path of the ray till it emerges out of the prism B.
Trace a ray of light incident at 30° on a surface if travelling from glass to air. What is the angle of refraction in this case? (R.I. for glass = 3/2).
