text: below is an answer. i don't understand. explain.? "crown glass" is a soda-lime glass used to make lenses and prisms. it has a lower refractive index and less dispersion than flint glass, but is more durable. you can answer all your other questions using only the information in that sentence.   so for prisms, is crown glass or flint glass better to use in order to show a nice, hot, bright, spectrum and to study it? flint glass is better.    in order to make a crisp, bright spectrum, you need to have a high refractive index -- this means that it will bend the light more as you scan across the wavelengths than the crown glass.  the crown glass will not bend the light as much, so the spectrum will be more "mushed together" than that from the flint glass.