JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी Question Bank Self Evaluation Test - Wave Optics

  • question_answer
    In YDSE a light containing two wavelengths 500 nm and 700 nm are used. Find the minimum distance where maxima of two wavelengths coincide. Given \[D/d={{10}^{3}}\], where D is the distance between the slits and the screen and d is the distance between the slits.

    A) 1.2 m

    B) 3.5 mm

    C) 2.8 cm

    D) 8.1 mm

    Correct Answer: B

    Solution :

    [b] At the place where maxima for both the wavelengths coincide, y will be same for both the maxima, i.e., \[\frac{{{n}_{1}}{{\lambda }_{1}}D}{d}=\frac{{{n}_{2}}{{\lambda }_{2}}D}{d}\Rightarrow \frac{{{n}_{1}}}{{{n}_{2}}}=\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{700}{500}=\frac{7}{5}\] Minimum integral value of \[{{n}_{2}}\]is 5. Minimum distance of maxima of the two Wave lengths fr 1 om central fringe \[\frac{{{n}_{1}}{{\lambda }_{2}}D}{d}=5\times 700\times {{10}^{-9}}\times {{10}^{3}}=3.5mm.\]


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