![]() The refractive index of diamond with respect to air is 2.42. Total internal reflection is the main cause of the brilliance of diamonds. Hence for total internal reflection to take place (i) light must travel from a denser medium to a rarer medium and (ii) the angle of incidence inside the denser medium must be greater than the critical angle i.e. If the denser medium is glass, c = sin -1(1/µ g) ![]() If µ d is the refractive index of the denser medium then, from Snell’s Law, the refractive index of air with respect to the denser medium is given by,ġ/ µ d = sin i/sin r (Since, µ a = 1 for air) This is called total internal reflection. If i is increased further, refraction is not possible and the incident ray is totally reflected into the same medium itself. The angle of incidence in the denser medium at which the refracted ray just grazes the surface of separation is called the critical angle c of the denser medium. Now the refracted ray OC is bent so much away from the normal and it grazes the surface of separation of two media. If the angle of incidence is gradually increased, the angle of refraction r will also gradually increase and at a certain stage r becomes 90 o. ![]() When a ray of light AO passes from an optically denser medium to a rarer medium, at the interface XY, it is partly reflected back into the same medium along OB and partly refracted into the rarer medium along OC as shown in figure. Concepts of Physics by HC Verma for JEE.IIT JEE Coaching For Foundation Classes.
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