JEE Main & Advanced JEE Main Paper (Held on 09-4-2019 Morning)

  • question_answer The figure shows a Young's double slit experimental setup. It is observed that when a thin transparent sheet of thickness t and refractive index μ is put in front of one of the slits, the central maximum gest shifted by a distance equal to n fringe widths. If the wavelength of light used is \[\lambda ,t\]will be : [JEE Main 9-4-2019 Morning]

    A) \[\frac{2D\lambda }{a(\mu -1)}\]                  

    B) \[\frac{D\lambda }{a(\mu -1)}\]

    C) \[\frac{2nD\lambda }{a(\mu -1)}\]                

    D) \[\frac{nD\lambda }{a(\mu -1)}\]

    Correct Answer: B

    Solution :

    Path difference at central maxima \[\Delta x=(\mu 1)t,\] whole pattern will shift by same amount which will be given by \[(\mu 1)t\frac{D}{d}=n\frac{\lambda D}{d},\]according to the question \[t=\frac{n\lambda }{(\mu -1)}\] no option is matching, therefore question should be awarded bonus. \[\therefore \] Correct Option should be (Bonus)


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