JEE Main & Advanced Physics Ray Optics Question Bank Mock Test - Geometrical Optics

  • question_answer
    A prism of refractive index \[\mu \] and angle A is placed in the minimum deviation position. If the angle of minimum deviation is A, then the value of A in terms of\[\mu \] is

    A) \[{{\sin }^{-1}}\left( \frac{\mu }{2} \right)\]       

    B) \[{{\sin }^{-1}}\sqrt{\frac{\mu -1}{2}}\]

    C) \[2{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]     

    D) \[{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]

    Correct Answer: C

    Solution :

    [c] Given \[{{\delta }_{m}}=A,\]as \[\mu =\frac{\sin \left( \frac{A+{{\delta }_{m}}}{2} \right)}{\sin \left( \frac{A}{2} \right)}\] \[\Rightarrow \mu =\frac{\sin \left( \frac{A+A}{2} \right)}{\sin \left( \frac{A}{2} \right)}=2\cos \frac{A}{2}\] \[\Rightarrow A=2{{\cos }^{-1}}\left( \frac{\mu }{2} \right)\]


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