NEET Physics Wave Optics / तरंग प्रकाशिकी NEET PYQ-Wave Optics

  • question_answer
    In the Young's double-slit experiment, the intensity of light at a point on the screen (where the path difference is \[\lambda \]) is K, (\[\lambda \] being the wavelength of light used). The intensity at a point where the path difference is \[\lambda ,/4,\] will be                                                                                                                                    [NEET 2014]

    A)  K                    

    B)       K/4     

    C)  K/2     

    D)  zero

    Correct Answer: C

    Solution :

    For net intensity
    \[l'=4{{l}_{0}}{{\cos }^{2}}\frac{\phi }{2}\left( \phi =\frac{2\pi }{\lambda }\times \lambda  \right)\]
    For the first case,
    \[K=4{{l}_{0}}{{\cos }^{2}}[\pi ]\]
    \[K=4{{l}_{0}}\]                                   …(i)
    For the second case
                \[K'=4{{l}_{0}}{{\cos }^{2}}\left( \frac{\pi /2}{2} \right)\left( \phi =\frac{2\pi }{\lambda }\times \frac{\lambda }{4} \right)\]
    \[4{{l}_{0}}{{\cos }^{2}}(\pi /2)\]
    \[K'=2{{l}_{0}}\]                      …(ii)
    Comparing Eqs. (i) and (ii)
    \[K'=K/2\]


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