Phosphor coating on the wall of a fluorescent lamp emits the broad spectrum of v
ID: 581999 • Letter: P
Question
Phosphor coating on the wall of a fluorescent lamp emits the broad spectrum of visible lights by absorbing the ultraviolet (UV) light emitted by the mercury vapor. Considering that mercury is an environmental hazard, and knowing that Neon lamp produces bright red light, a lamp engineer proposes that we should develop a mercury-free fluorescent lamp by utilizing phosphors that can convert the red light to green and blue wavelengths. Considering that uniform mixture of red, green and blue light leads to white light, utilizing such phosphors would make it possible to convert the red Neon light into white light. Is this proposal feasible? Why do we not have such fluorescent lamps around us?
Explanation / Answer
Such a proposal is possible in principle but it may still not be a viable replacement for mercury in general purpose fluorescent lamps as the efficiency will be much less than that of a normal mercury-based fluorescent lamp and therefore, this technology will be environmentally counterproductive for general lighting applications. Also, a mercury-free fluorescent lamp would consume more power for the same light output than a fluorescent lamp.