Why does a spectroscope need a diffraction grating.

Well, because the diffraction grating allows optical spectroscopy and a grating disperses light of different wavelengths to give. Wavelengths like any wavelength, a narrow fringe.

i think it's the first one because doctors aren't the ones who get rid of the old needles. most of them time it's not even doctors who give you shots, it's nurses.

the answer is true because it was true