Question

Light of wavelength 660 nm passes through two narrow slits 0.65 mm apart. The screen is 2.55 m away. A second source of unknown wavelength produces its second-order fringe 1.17 mm closer to the central maximum than the 660 nm light. What is the wavelength of the unknown light?

Express your answer to three significant figures and include the appropriate units.

Answer 1

Step-by-step 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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