JCECE Engineering JCECE Engineering Solved Paper-2006

  • question_answer
    The fringe width for red light is approximately how many times that for violet light in Young's slit experiment?

    A)  \[2\] times                        

    B)  \[3\] times

    C)   Equal                                  

    D)   \[1/2\] times

    Correct Answer: A

    Solution :

    The fringe width \[(W)\] is given by                 \[W=\frac{D\lambda }{d}\] where \[\lambda \] is wavelength, \[d\] the distance between coherent sources, \[D\] the distance between source and screen. \[\therefore \]  \[\frac{{{W}_{R}}}{{{W}_{V}}}=\frac{{{\lambda }_{R}}}{{{\lambda }_{V}}}\] \[{{\lambda }_{R}}\](red light) is\[6400-7900{\AA}\] \[{{\lambda }_{V}}\](violet light) is\[4000-4500{\AA}\] \[\therefore \]  \[{{W}_{R}}\approx 2{{W}_{V}}\]


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