Manipal Medical Manipal Medical Solved Paper-2005

  • question_answer
    In Youngs double slit experiment, the spacing between the slits is d and wave length of light used is\[6000\overset{o}{\mathop{\text{A}}}\,\]. If the angular width of a fringe formed on a distant screen is\[1{}^\circ ,\] then value of d is:

    A)  1 mm           

    B)  0.0.5 mm

    C)  0.03 mm        

    D)  0.01 mm

    Correct Answer: C

    Solution :

     \[\sin \theta \simeq \theta \frac{y}{D}\] So,         \[\Delta \theta =\frac{\Delta y}{D}\] Angular fringe width\[{{\theta }_{0}}=\Delta \theta \](width\[\Delta y=\beta \]) \[{{\theta }_{0}}=\frac{\beta }{D}=\frac{D\lambda }{d}\times \frac{1}{D}=\frac{\lambda }{d}\] \[{{\theta }_{0}}=1{}^\circ =\frac{\pi }{180}rad\] And \[\lambda =6\times {{10}^{-7}}m\] \[d=\frac{\lambda }{{{\theta }_{0}}}=\frac{180}{\pi }\times 6\times {{10}^{-7}}\] \[=3.44\times {{10}^{-5}}m\] \[=0.03\text{ }mm\]


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