There is no such thing as “black light wavelength”—so why do black T-shirts, black crayons, and black marking pens look black? Investigate a variety of black ink markers, and find out why they look ...

How do black lights work? Black lights emit ultraviolet (UV) light, which has a shorter wavelength than visible light. Specifically, black lights emit UVA, with a wavelength between 315-400 ...