NEET Sample Paper NEET Sample Test Paper-42

  • question_answer
                If the angle of incidence is twice the angle of refraction in a medium of refractive index u, then angle of incidence:

    A) \[2\,Co{{s}^{-1}}\frac{\mu }{2}\]                    

    B) \[2\,Si{{n}^{-1}}\frac{\mu }{2}\]

    C) \[2\,Co{{s}^{-1}}\mu \]                       

    D) \[2\,Si{{n}^{-1}}\mu \]

    Correct Answer: A

    Solution :

    Angle of incidence =2 (angle of refraction) i=2r Apply snell?s law \[\Rightarrow {{\mu }_{1}}\operatorname{Sin}\,i={{\mu }_{2}}Sin\,\operatorname{r}\] \[\Rightarrow 1\times \operatorname{Sin}\,2\operatorname{r}={{\mu }_{2}}Sin\,\operatorname{r}{{\mu }_{2}}=1(assum\,air)\] \[\Rightarrow \operatorname{r}=\frac{{{\cos }^{-1}}\mu }{2}\] \[\Rightarrow \operatorname{r}=\frac{i}{2}\] \[\operatorname{i}=2{{\cos }^{-1}}\frac{\mu }{2}\]


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