JEE Main & Advanced JEE Main Online Paper (Held On 08 April 2018)

  • question_answer
    Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be\[\frac{\text{I}}{\text{2}}\]. Now another identical polarizer C is placed between A and B. The intensity beyond B is now found to be\[\frac{\text{I}}{8}\]. The angle between polarizer A and C is: [JEE Main Online 08-04-2018]

    A)  \[45{}^\circ \]                                  

    B)  \[60{}^\circ \]

    C)  \[0{}^\circ \]                        

    D)  \[30{}^\circ \]

    Correct Answer: A

    Solution :

    Polarizing axis of A & B polarizer are parallel to each other \[{{\text{I}}_{\text{1}}}\text{=}\frac{\text{I}}{\text{2}}\text{co}{{\text{s}}^{\text{2}}}\theta \] \[\frac{I}{8}={{I}_{1}}{{\cos }^{2}}\theta \] \[\frac{I}{8}=\frac{I}{2}{{\cos }^{4}}\theta \] \[\cos \theta =\frac{1}{\sqrt{2}}\] \[\]


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