i would like to ask a que regarding pysical optic,so lets nt beating abt the bush, QUE:A laser beam is incident on a 1.50 x 10^4 grove per inch diffraction grating.The wavelength of the light produced by the laser is 6.30nm and the interference pattern is observed on a screen 2.00m from the grating.Determine maximum number of fringes that can be observed? here goes the solution but im nt really clear of the solution: d sin teta = m X lamda sin teta=m.lamda.N/l <1 m< l/2N ans is 2.69. tis is my que,why d=l/N wat does it represents for l/N ???then why do sin teta=m.lamda.N/l <1???why?is it because of polarized light is lesser than 1 while unpolarized light bigger than 1???thanks for your help!!!