NEET Sample Paper NEET Sample Test Paper-14

  • question_answer Light of wavelength\[\lambda \]is incident on a slit of width d. The resulting diffraction pattern is observed on a screen at a distance D. The linear width of the principal maximum is equal to the width of the slit, if D equals

    A)  \[\frac{d}{\lambda }\]                                   

    B)  \[\frac{2\lambda }{d}\]

    C)  \[\frac{{{d}^{2}}}{2\lambda }\]                           

    D)  \[\frac{2{{\lambda }^{2}}}{d}\]

    Correct Answer: C

    Solution :

    If\[D>>d,\]the linear width of the central principal maximum = angular width XD \[\therefore \]Linear width of the principal maximan\[=\frac{2\lambda D}{d}.\] The linear width of the principal maximum will be equal to slit width for a value of D given by\[\frac{2\lambda D}{d}=d\]or \[D=\frac{{{d}^{2}}}{2\lambda }.\] Hence, the correction option is [c].


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