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JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी Question Bank Diffraction of Light

  • question_answer
    In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will                                                                                             [RPMT 2002]

    A)            Increase                                 

    B)            Decrease

    C)            Remain constant                

    D)            None of these

    Correct Answer: B

    Solution :

     \[A=n\pi \,d\lambda \] \[\Rightarrow nd=\frac{A}{\pi \,\lambda }\]= constant \[\Rightarrow n\propto \frac{1}{d}\] \[(n=\] number of blocked \[HPZ)\] on decreasing \[d,\] \[n\] increases, hence intensity decreases.


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