A light source, which emits two wavelengths λ 1 = 400   n m and λ 2 = 600   n m , is…

A light source, which emits two wavelengths λ1=400 nm and λ2=600 nm , is used in a Young's double slit experiment. If recorded fringe widths for λ1 and λ2 are β1 and β2 and the number of fringes for them within a distance y on one side of the central maximum are m1 and m2 , respectively, then
  1. β2>β1
  2. m1>m2
  3. From the central maximum, 3rd maximum of λ2 overlaps with 5th minimum of λ1
  4. The angular separation of fringes for λ1 is greater than λ2

Solution

β=Dλd
∵λ2>λ1⇒β2>β1
Also m1β1=m2β2⇒m1>m2
Also 3Dd600 nm=2×5-1D2d400 nm
Angular width θ=λd

Asked in: JEE Advanced 2014 (Paper 1)

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