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A diffraction grating has `1.26xx10^(4)` rulings uniformly spaced over width w=25.4 mm. It is illuminated at normal incidence by blue light of wavelength 450 nm At what angles to the central axis do the second order maxima occur |
Answer» The grafting spacing d is `d=w/N=(25.4xx10^(-3))/(1.26xx10^(4))=20.16xx10^(-6)m=2016nm` The second order maxima corresponds to `n=2` For `lambda=450nm` we have `d sin theta=2lambda rArr theta=sin^(-1)((2lambda)/d)` `rArrtheta=sin^(-1)((2xx450xx10^(-9))/(2.016xx10^(-6)))` `:.Angle theta approx 27^(@)` |
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