# Diffraction grating

by jdog6
Tags: diffraction, grating
 P: 187 the helium is used instead of a light bulb because a certain element only emits certain wavelengths of light while the bulb would emit all wavelengths, and even if you were to split this with a prism you would still see all the colors and not specific ones. the order of diffraction is correct by what you said, since the n in the equation $$d sin\theta = n\lambda$$ refers to the order of diffraction, where n=1 is the first, n=2 is the second and so on. the grating constant k, is simply 1/d. d is the distance between slits and k, is the number of slits per unit length.