Aritra

Thanks.

Hello everyone, On asking my teacher, I was told that, UV light readable ink works by changing the frequency of the ultraviolet light to something inside the visible spectrum. While I understood the basic concept, which, after all, was very simple, I couldn't understand how the chemical reduces the frequency of waves. On refraction, the velocity of the light changes and, this is understandable. However, neither refraction, nor reflection change the frequency of light. Also, does this mean that, say, by passing red light through this chemical, infra red light could be produced? Thanks