Ultraviolet light is typically divided into three categories. UV-A, with wavelengths between 400 nm and 320 nm, has been linked with malignant melanomas. UV-B radiation, which is the primary cause of sunburn and other skin cancers, has wavelengths between 320 nm and 280 nm. Finally, the region known as UV-C extends to wavelengths of 100 nm.
(a) Find the range of frequencies for UV-B radiation.
(b) In which of these three categories does radiation with a frequency of 7.9 × 1014 Hz belong?