REFRACTION OF LIGHT : REFRACTION OF LIGHT Refraction is the bending of light rays when passing from one transparent medium to another
Slide 2 : Welcome
Slide 3 : We see a verity of objects in the world around us.
But we are unable to see anything in the dark room.
During day sunlight help us to see objects.
An object reflects the light that falls on it. This reflected light ,when received by our eyes enables us to see things.
Slide 4 : By observing common optical phenomena around us
Image formation by mirrors
The twinkling stars
The beautiful colors of rainbow
Bending of light by a medium……….
We may conclude that …..
. : . Light seems to be travel in straight lines.
Slide 6 : Light seems to travel along straight line paths in a transparent medium.
What happens when light enters from one transparent medium to another???
Refraction of light : Refraction of light
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Slide 11 : Let us consider the case of the apparent displacement of a pencil, partially immersed in water . The light reaching you from the portion of the pencil inside water seems to come from a different direction, compared to the part above the water.
Slide 12 : That means light changes its path when it enters from the air to the water.
Slide 13 : REFRACTION IS DUE TO CHANGE IN THE SPEED OF LIGHT AS IT ENTERS FROM ONE TRANSPARENT MEDIUM TO ANOTHER
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Refraction of light : Refraction of light Refraction is the bending of light rays when passing from one transparent medium to another.
Slide 18 : Any questions ??
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REFRACTION THROUGH A GLASS SLAB : REFRACTION THROUGH A GLASS SLAB
Refraction through a glass slab : Refraction through a glass slab
Slide 22 : Any Questions ?
Slide 23 : Experiments shows that refraction of light occurs according to certain laws.
The incident ray , the refracted ray and the normal to the interface of two transparent media at the point of incidence , all lie in the same plane.
The ratio of sine of angle of incidence to the angle of refraction is a constant, for the light of a given color and for the given pair of media
Slide 24 : If ‘i’ is the angle of incidence and ‘r’ is the angle of refraction
sin i/sin r = constant.
This constant value is called the refractive e index of the medium with respect to the first.
Refractive index : Refractive index The refractive e index can be linked to an important physical quantity , the relative speed of propagation of light in different media. It turns out that light propagates with different speeds in different media. In air, the speed of light is only marginally less compared to that in vacuum. It reduces considerably in glass or water.
Slide 26 : Consider a ray of light travelling from medium 1 to medium 2. let v1 be the speed of light in medium 1 , and V2 be the speed light in medium 2. The refractive index of medium 2 with respect to medium 1 is given by the ratio of the speed of light in medium 1 and the speed light in medium 2. This is usually represented by the symbol n12.
Slide 27 : n12=speed of light in medium 1/speed of light in medium 2.
ie= ?1/v2
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Atmospheric refraction : Atmospheric refraction The twinkling of a star is due to atmospheric refraction of starlight. The star light on entering the earth's atmosphere , undergoes refraction continuously before it reaches the earth .
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Slide 36 : Thank you