CMC Medical CMC-Medical Ludhiana Solved Paper-2015

  • question_answer
    The light of wavelength 560 nm goes through a pin hole of diameter 0.20 mm and falls on a wall at a distance of 2m. The radius of central bright fringe formed on the wall, will be

    A)  137 cm                

    B)  0.683

    C)  2.07 cm               

    D)  1.98 cm

    Correct Answer: A

    Solution :

                    Given,   \[\lambda =560\,nm=560\times {{10}^{-9}}m\] \[d=0.20\,\,mm=2\times {{10}^{-4}}m\] and                            \[D=2\,m\] As the radius of image disc \[R=1.22\frac{\lambda D}{b}\] \[=\frac{1.22\times 560\times {{10}^{-9}}\times 2}{2\times {{10}^{-4}}}\] \[=6.832\times {{10}^{-3}}m\] \[=0.683\,cm\] So, the radius of central bright fring formed on the wall \[=2R=2\times 0.683=1.37\,cm\]


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