Circuit Diagram Uv Light - A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow.A fluorescent lamp converts electrical energy into useful light much more efficiently. Wave interference is a phenomenon which occurs when two waves meet while traveling along the same medium. Wave interference can be constructive or destructive. Constructive interference occurs at locations where the two interfering waves are displaced in the same direction - either both up or both.