Q11 of 25 Page 11

Sky appears blue to an observer from the surface of the earth. ( CBSE 2010)

Sky appears blue due to the phenomenon of scattering of light by the molecules of air and other particles in the atmosphere and since they have a size smaller than the wavelength of the visible light, so the particles scatters blue color light rays effectively than that of longer wavelength color.

The color of the sky is dark instead of blue to an astronaut because there is no presence of atmosphere in the sky due to which the scattering of light doesn’t occur and the sky appears dark.

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9

A narrow beam of light produces a spectrum XY on passing through a triangular glass prism.


(a) State the colour at X and Y.


(b) Why do the different components of white light bend through different angles with respect to the incident beam of light?
( CBSE 2007)

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What is meant by advance sunrise and delayed sunset ? Draw a labelled diagram to explain this phenomenon. ( CBSE 2015, 2010)

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A student is unable read the blackboard placed at a distance of approximately 4 m from him. Name the defect of the vision the boy is suffering from. ( CBSE 2015, 2014)

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What is atomic refraction? use this phenomenon to explain twinkling of star, advance sunrise and delayed sunset. Draw a ray diagram to illustrate your answer? ( CBSE 2016, 2015, 2014, 2012, 2011)