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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
Draw diagrams to show the refraction of light from glass to air. In diagram, label the incident ray, refracted ray, the angle of incidence (i) and the angle of refraction (r).
How does the angle of minimum deviation produces by a prism change with increase in :
the refracting angle of prism?
What do you understand by the statement the refractive index of glass is 1.5 for white 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)`
“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.
The critical angle for glass-air interface is :
Rewrite the following statement by selecting the correct option:
If a ray of light strikes a glass slab at an angle of 600 with the surface of the slab, the angle of incidence must be __________________.
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.
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.
