InterviewSolution
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InterviewSolution
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The speed of light in media `M_1` and `M_2` are `1.5 xx 10^8 m//s and 2.0 xx 10^8 m//s` respectively. A ray of light enters from medium `M_1` to `M_2` at an incidence angle `i`. If the ray suffers total internal reflection, the value of `i` is.A. Equal to `sin^-1((2)/(3))`B. Equal to or less than `sin^-1((3)/(5))`C. Equal to or grater than `sin^-1((3)/(4))`D. Less than `sin^-1((2)/(3))` |
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Answer» Correct Answer - C Given, `v_1 = 1.5 xx 10^8 m//s , v_2 = 2.0 xx 10^8 m//s` Refractive index for medium `M_1` is `mu = ( c)/(v_1) = (3 xx 10^8)/(1.5 xx 10^8) = 2` Refractive index for medium `M_2` is `mu_2 = ( c)/(v_2)=(3 xx 10^8)/(2.0 xx 10^8) = (3)/(2)` If `i` is the angle of incidence and `C` is the critical angle then for total internal reflection. `sin i ge sin C` But `sin C = mu_2//mu_1` `:. sin i ge (mu_2)/(mu_1) ge (3//2)/(2)` or `i ge sin^-1((3)/(4))`. |
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