|What would you hypothesize the effects of black light bulbs to be on the tanning of human skin?
I would expect that certain black light sources would cause tanning with only modest burning while other black light sources would cause burning with only modest tanning. Black light—also known as ultraviolet light—consists of very energetic light particles. The particles or photons of ultraviolet light contain enough energy to break chemical bonds and rearrange molecules. When you're exposed to such energetic light, it causes damage to molecules in your skin cells and your skin may respond by darkening in the process we call "tanning." But ultraviolet light is a general term that covers a broad range of wavelengths and photon energies. Long wavelength/low energy ultraviolet light tends to cause tanning while short wavelength/high energy ultraviolet light tends to cause burning—it directly kills cells. But these differences aren't sharp and any ultraviolet light will cause some amount of skin damage.