NEET Sample Paper NEET Sample Test Paper-35

  • question_answer
    An equilateral prism has \[\mu =\sqrt{3},\] its angle of minimum deviation is:

    A)  \[{{75}^{o}}\]                

    B)  \[{{60}^{o}}\]

    C)  \[{{90}^{o}}\]                

    D)  \[{{45}^{o}}\]

    Correct Answer: B

    Solution :

    For a prism RI is given by \[\mu =\frac{\sin \left( \frac{A+\delta m}{2} \right)}{\sin \left( \frac{A}{2} \right)}\] ?..(i) Where,           A = angle of prism Here,             \[A={{60}^{o}},\mu =\sqrt{3}\] Putting the given value in equation (i), we get, \[\sqrt{3}=\frac{\sin \left( \frac{{{60}^{o}}+\delta m}{2} \right)}{\sin {{30}^{o}}}\] \[\sqrt{3}\times \sin {{30}^{o}}=\sin \left( \frac{{{60}^{o}}+\delta m}{2} \right)\] \[=\sin \left( \frac{{{60}^{o}}+\delta m}{2} \right)\] \[=\frac{\sqrt{3}}{2}=\sin {{60}^{o}}\] \[\Rightarrow \] \[\frac{{{60}^{o}}+\delta m}{2}={{60}^{o}}\] \[\Rightarrow \] \[{{60}^{o}}+\delta m={{120}^{o}}\] \[\Rightarrow \] \[\delta m={{120}^{o}}-{{60}^{o}}={{60}^{o}}\]


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