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JEE Main 2014 (12 Apr, Shift 1) · Diffraction at a Single Slit

Diffraction at a Single Slit question from JEE Main 2014 (12 Apr, Shift 1)

Q83JEE Main 2014 · 12 APR · SHIFT 1Medium

Diffraction at a Single Slit

In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum of some other wavelength. If wavelength of red light is 6600 A˚\text{Å}, then wavelength of first maximum will be:

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Answer: (b)

  1. First minimum of red: asin⁡θ=λra\sin\theta = \lambda_r; first maximum of other light: asin⁡θ=3λ′2a\sin\theta = \dfrac{3\lambda'}{2}
  2. Same angle: λr=3λ′2⇒λ′=2×66003\lambda_r = \dfrac{3\lambda'}{2} \Rightarrow \lambda' = \dfrac{2 \times 6600}{3}
  3. So the answer is (b) 44004400 Å.
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