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

  • question_answer
    A plane wave front \[(\lambda =6\times {{10}^{-7}}m)\] falls on a slit 0.4 mm wide. A convex lens of focal length 0.8 m placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum?

    A) 6 mm   

    B) 12 mm

    C) 3 mm   

    D) 9 mm

    Correct Answer: A

    Solution :

    [a] For secondary maxima d \[\sin \theta =\frac{5\lambda }{2}\] \[\Rightarrow d\theta =d.\frac{x}{D(\approx f)}=\frac{5\lambda }{2}\] \[\Rightarrow 2x=\frac{5\lambda f}{d}=\frac{5\times 0.8\times {{10}^{-7}}}{4\times {{10}^{-4}}}=6\times {{10}^{-3}}m=6mm\]


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