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प्रश्न
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'?
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उत्तर
When light travels from one medium (air) to another medium (glass), it bends towards the normal. The extent of bending of light depends upon the speed of light (v2) in the second medium, compared to the speed of light (v1) in the first medium. The refractive index of the second medium w.r.t. the first medium (n21) is given by
n21 = Speed of light (v1) in first medium / speed of light (v2) in second medium
The refractive index of glass is typically around 1.5, meaning that light in glass travels at
c / 1.5 = 200,000 km/s. A low value of refractive index also indicates a large critical angle at the glass-air interface.
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संबंधित प्रश्न
Write a relationship between the angle of incidence and angle of refractions for a given pair of media
Draw the diagram given below and clearly show the path taken by the emergent ray.
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?
In an experiment of finding the refractive index of glass, if blue light is replaced by the red light, how will the refractive index of glass change? Give reason in support of your answer.
Can the absolute refractive index of a medium be less than one?
How does the angle of deviation produced by a prism depend on the angle of incidence of light at the prism surface? Draw a graph to illustrate your answer.
A ray of light strikes the surface of a rectangular glass slab such that the angle of incidence in air is
- 0°,
- 45°.
In each case, draw a diagram to show the path taken by the ray as it passes through the glass slab and emerges from it.
