posted by anonymous .
Why is white light separated into a spectrum of colors when it is passed through a diffraction grating?
The diffraction angle (theta) is given by
n x (lambda) = d sine(theta)
lambda = wavelength
theta = diffraction angle
d = grating spacing
n = order (1,2,3 etc.)
so each wavelength is diffracted through a slightly different angle. If the incident light is white light then you will see a rainbow at each value of n.