5.(15pts) Using the R formula for the resolution of a grating, what minimum widt

Question

5.(15pts) Using the R formula for the resolution of a grating, what minimum width of a grating, in mm, must be illuminated to resolve the lines in question 3 in first order and second order if the grating has 1200 lines per mm?

This is question 3 mentioned above '
(a)10pts If the angle of incidence of light on a diffraction grating is 0.0o what is the wavelength of light (in nm) which will be reflected by 35.5o in first order if the grating has 1450 groves per millimeter.
(a)10pts. Light impinges on a 1450 line per mm diffraction grating at an angle of incidence of 42 degrees. What wavelength, in nm, will be reflected in the first order at an angle of 12 degrees on the other side of the normal to the grating.
(b)10 pts. At what angle would the second order light of the same wavelength be reflected on the same side of the normal to the grating as the incident light?

Explanation / Answer

i) Angle of incidence of light on a diffraction grating = 0.00

        order of the spectrum = 1

       Angle of reflection = 35.50

       No. of grooves on grating per mm = 1450

       So, d = 0.1/1450 = 6.89 x 10-5 cm

     According to equation of grating d sin =n

   Here, d = 14500 grooves/cm

               = 35.50

               n = 1

So, 6.89 x 10-5 x sin (35.50) = 1 x

Hence, = 14500 x 0.58 = 3.992 x 10-5 cm   

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