<prompt> Woods lamp has a frequency of -250 nm300 nm320 nm360 nm  <response>: WOODS LAMP Hand held device used to diagnose various dermatological conditions.It is a mercury vapour long wave,ultraviolet lamp with an inbuilt woods filter made of barium silicate with 9 nickel oxide. Opaque to all wavelengths except those between 320 nm and 400 nm with a peak at 365 nm. Flourescence occurs when woods light is absorbed and radiation of longer wavelengths is emitted.Examination done in dark room. Iadvl textbook of dermatology page 109 