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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
Why do we get a spectrum of seven colors when white light is dispersed by a prism?
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.
Fig 4.31 below shows a light ray of single colour incident normally on two prisms A and B. In each case draw the path of the ray of light as it enters and emerges out of the prism. Mark the angle wherever necessary.
While performing the experiment on tracing the path of a ray of light through a rectangular glass slab, in which of the following experimental set-ups is a student likely to get best results? P1 and P2 are the positions of pins fixed by him.
(A) I
(B) II
(C) III
(D) IV
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.
A ray of light moves from a rare medium to a dense medium as shown in the diagram below. Write down the number of the ray which represents the partially reflected ray.
Calculate the velocity of light in a glass block of refractive index 1.5. (Velocity of light in air = 3 × 108 m/s)
Write the approximate values of speed of light in (i) air and (ii) glass. Use these values to calculate the refractive index of glass with respect to air.
