What is the highest spectral order that can be seen if a grating with 6500 slits per cm is illuminated with 633-nm laser light? Assume normal incidence.

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Aryan Novak · Accepted Answer

Given values:Number of slits per centimeter,   N  =  6500   slits/cmWavelength,   λ  =  633   nmAngle of diffraction,   θ  =      90    ∘  The phenomenon of bending of the light waves around the cornerns of obstacle is called diffraction. The condition for diffraction maximum is given by,  n  λ  =  d  sin  ⁡  θWhere,n= Order of diffraction  λ  = Wavelength of lightd= Separation between the slits  θ  = Angle of diffractionThe number of slits per centimeter is equal to the separation between the slits.Number of slits per cm,   N  =      1    d  Substituting equation  n  λ  =            sin      ⁡      θ        N      n  =            sin      ⁡      θ              λ      N      Substituting number of slits per centimeter, wavelength and angle of diffraction in equation  n  =            sin      ⁡              90        ∘                    6500      ×              10        2             slits/m      ×      633      ×              10                  −          9                     m          =  2.43    ≈  2

What is the highest spectral order illuminated with 633-nm laser light?

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