Selina Concise ICSE Solutions for Class 8 Physics Chapter 5 Light Energy • Light is a form of energy which produces in us the sensation of sight i.e. we can see objects only when light falls on them and then reflected into our eye. • Velocity of light in air or in vacuum is 300000 km per second. Or 3 x 108 ms-1 • As light passes into different mediums its speed changes and depends upon the density of medium i.e. it decreases with increase in density i.e. it is 2.25 × 108 m/s in water and 2 x 108 ms-1 in glass as water is denser than air ( = 1.33 ) and glass is still optically denser than water ( =1.5 ) i.e. slower in water and still slower in glass. • Light travels in a straight line. • As light travels from one transparent medium to other transparent medium and falls oblique at another medium, its path changes and this change in path is called REFRACTI...
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