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प्रश्न
Explain briefly what causes the twinkling of stars at night.
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उत्तर
Stars are very far from us. The light ray coming from a star undergoes successive refractions on entering the earth’s atmosphere and bends towards the normal. Hence, an apparent image of the star is seen. Simultaneously due to the movement of air, the refractive index of layers of atmosphere keeps on changing, i.e., the apparent position of star keeps changing. Thus, the star appears to twinkle.
संबंधित प्रश्न
Name a prism required for obtaining a spectrum of Ultraviolet light.
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?
With the help of diagram of the principal section of a prism, indicate its refracting surfaces, refracting edge and base.
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?
Observe the figure and write accurate conclusion regarding refraction of light.
In the fig., PO is a ray of light incident on a rectangular glass block.
(a) Complete the path of the ray through the block.
(b) 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?
(c) Mark angle of emergence by the letter e. How are the angles i and e related?
(d) Which two rays are parallel to each other? Name them.
(e) Indicate in the diagram the lateral displacement between the emergent ray and the incident ray.
Draw a ray diagram showing the lateral displacement of a ray of light when it passes through a parallel sided glass slab.
The diagram shows the path of a ray of light through a rectangular glass block placed in a liquid of uniform density.
What should be the rate of the speed of light through the liquid to the speed through the glass so that there is no refraction of light at the boundaries of the glass block when the system is illuminated by the light of one colour?
