Question

what is the range of frequencies of visible light?

Answer 1

http://en.wikipedia.org/wiki/Electromagnetic_spectrum
there can't be better answer than this one.

Answer 2

Search this on google pictures and you get a lot of nice stuff like: http://www.beercolor.com/color_basics1_files/image002.jpg
It depend on how accurate you want your numbers to be.

Answer 3

400-790 THz, but it's more likely to be referred to in terms of its wavelength. 380-750nm (nanometers)