There are two categories of ultraviolet light. Ultraviolet A ( UVA ) has a wavelength ranging from 320 nm to 400nm . It is not so harmful to the skin and is necessary for the production of vitamin D. UVB, with a wavelength between 280nm and 320nm , is much more dangerous, because it causes skin cancer.
Find the frequency ranges of UVB. (fmin, fmax)
What are the ranges of the wave numbers for UVA? (kmin, kmax)
What are the ranges of the wave numbers for UVB? (kmin, kmax)