Determination of Wavelengths of Spectral Lines of White Light: Monochromatic light is now replaced by the given source of white light. The source emits radiations of different wavelengths, then the beam gets dispersed by grating and a spectrum of constituent wavelengths is obtained as shown in Figure.
Fig: Diffraction of white light
knowing N, wave length of any line can be calculated from the relation: λ = sinθ/Nm
