Since the hot tungsten would quickly burn away if it were exposed to oxygen, it must be placed in a sealed glass bulb which is either evacuated or filled with a gas that won t let it burn. Another common type of light is the fluorescent lamp. A fluorescent lamp is a glass tube filled with argon gas and a tough of mercury. The UV light then strikes the inside of the tube, which is coated with a phosphor. The phosphor glows, giving off the light we see.
Fluorescent lamps don t require high temperatures to produce light, like incandescent bulbs do.
Energy must be used in heating the incandescent bulb, and a large part of that energy is lost as heat, not light.