The wire's resistance to the flow of electricity causes it to become hot enough to glow and to give off light. The resistance causes the bulb to get hot. About 90 percent of the energy used by an incandescent bulb becomes heat and 10 percent becomes light. This fluorescent bulb lasts about 7,500 hours or eight times longer than the incandescent bulb.
Fluorescent lights are quite different from incandescent lights.
More of the energy of a fluorescent tube is converted into light and less into heat. By putting less heat in the air, fluorescent bulbs also save on air conditioning costs. Instead of a filament, inside, the fluorescent tube is a phosphor coating that converts ultraviolet energy into light. Over time, molecular vibrations inside the tube cause the phosphor coating to vibrate off. When the phosphor is used up, the tube won't light.