Answer:
Explanation:
Distance of 2 nd order fringe x₁ = 2 λ D/d [ λ is wave length , D is distance of screen , d is slit distance.
x₁ = 2 x 660 x10⁻⁹x 2.55/.65 x 10⁻³.= 5.17846 x 10⁻³ m.
Distance of fringe for 2nd radiation = 5.178 x 10⁻³ -1.17 x 10⁻³ = 4.008 x10⁻³
4.008 x 10⁻³ = 2 x λ x 2.55/.65 x 10⁻³
λ = 511 nm approx.
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