I have basically two doubts regarding diffraction and interference. First of all, according to my CIE A level Physics book, while the double slit experiment results in fringes that are more or less equally separated, a diffraction grating results in fringes that are not equally separated. Why is this the case? My second doubt is about passing white light through two slits or, any number of slits. What would be observed? Series of white light maximas and in place of dark fringes a series of spectra? (The 7 constituent colours).