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Draw a diagram showing the propagation of a plane wavefront from denser to a rarer medium and verify Snell's law of refraction. |
Answer» Solution : Let t be thetime taken bythewavefront to TRAVEL the distance BC. Thus BC = `v_(1)` t Similarly AE = `v_(2)`t For triangles ABC and AEC sin I = `(BC)/(AC)=(v_(1)t)/(AC) "and sin "r= (AE)/(AC)=(v_(2)t)/(AC)` where I and r are theangles of INCIDENCE and refraction respectively. `:. ("sin i")/("sin r")=(v_(1))/(v_(2))` If c is the speed of light in vacuum then `mu_(1)=(c)/(v_(1))orv_(1)=(c)/(v_(1))"and" " "mu_(2)=(c)/(nu_(2))` or `v_(2)= (c)/(mu_(2))` Here `mu_(1)` and `mu_(2)` are known as the refractive INDICES of medium 1 and medium 2 respectively. From equation (1) `("sin i")/("sin r")= (c)/(mu_(1))xxmu_(2)/(c)=mu_(2)/mu_(2) or mu_(1) " " "sin i" =mu_(2)` sin r This is the Snell's law of refration. |
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