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Question
(i) Define critical angle.
(ii) State one important factor which affects the critical angle of a given medium.
Solution
(i) The angle of incidence for which the angle of refraction is 90o is called critical angle.
`"_1 mu _2 = (sin i_c)/(sin (90^circ))`
`therefore (mu_2)/(mu_1) = (sini_c)/(1)`
` therefore 1/mu = sini_c " If " mu_2 = 1 mu_1 = mu`
` therefore i_c = sin^(-1) (1/mu)`
(ii) Relative refractive of the medium `("_1 mu_2)`1
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