What are the problems with conventional light bulbs?
A conventional light uses an incandescent bulb that works by passing an electric current through a tungsten filament to heat it. This glowing hot filament is what generates the light you see. Its typical luminous efficiency is only 5-10%, i.e., only 5-10% of the electric power input to the bulb being converted into the useable light. 90-95% of the radiant energy conversion is to heat, with a small amount to ultraviolet (UV) radiation. Its lifetime is typically 570 to 1000 hours. The luminous efficiency of a fluorescent lamp is about 20-27%, and the luminous efficiency of currently-developed high-brightness LEDs (HB LEDs) can reach 70-90%. The filament is reasonably rugged but if you drop your light you will most likely break the tiny filament, which results in the instant and total darkness. Even if you do not drop the light, the filament can only work for a small number of hours before it burns itself out. This will also result in unexpected instant darkness, which could quickly becom
