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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2006

  • question_answer
    A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is:

    A)  1.2 cm                                 

    B)  1.2 mm

    C)  2.4 cm                                 

    D)  2.4 mm

    Correct Answer: D

    Solution :

    \[\beta =\frac{\lambda D}{d}=\frac{600\times {{10}^{-9}}\times 2}{1\times {{10}^{-3}}}=12\times {{10}^{-4}}m\] So, distance between the first dark fringes on either side of the central bright fringe                 \[X=2\beta \]                 \[=2\times 12\times {{10}^{-4}}m\]                 \[=24\times {{10}^{-4}}m\]                 \[=2.4\,mm\]


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