The array seems endless — Even Thomas Edison would scratch his head over the choices in a typical home center's light bulb aisle.
The array seems endless - compact fluorescent and incandescent, clear and frosted, Edison base and candelabra, round and funnel-shaped.
So many options, so little information.
We're here to help you sort out the myriad bulbs out there. For simplicity's sake, we'll stick to general-service bulbs (also called Edison-base bulbs), the screw-in types that fit most lamps and light fixtures in a typical home. That's where most of the decision-making comes in, anyway, because most other fixtures require highly specific bulbs.
Household bulbs fall primarily into three categories - standard incandescent, halogen and compact fluorescent.
Standard incandescent is, of course, the bulb most of us know and use, essentially the kind Edison invented in 1879. It has a very thin tungsten filament, which heats and emits light as electrical current passes through it.
That works well, but there are drawbacks, said Steve Goldmacher, director of corporate communications for Philips Lighting Co., and Joe Rey-Barreau, educational consultant for the American Lighting Association and a member of the faculty of the University of Kentucky College of Design.
For one thing, the tungsten flakes off over time, causing the filament to fail. For another, tiny bits of evaporated tungsten end up adhering to the inside of the bulb as carbon, dulling the bulb. And the bulbs are highly inefficient: Only 5 percent of the energy produced goes into light, with the rest producing heat.
Since Edison's time, other technologies have come along to improve on the standard incandescent bulb. One is the halogen bulb, which is another form of incandescent bulb that contains a gas to improve the functioning. The gas, which contains a bit of halogen, does a couple of things, Goldmacher and Rey-Barreau said: It produces an interaction that prevents the carbon from settling on the inside of the bulb, and it causes the bits of evaporated tungsten to jump back onto the filament, essentially allowing the filament to regenerate.
For that process to happen, however, the bulb needs to get very hot. That's accomplished by making the bulb smaller, which puts the filament much closer to the glass and concentrates the heat, Rey-Barreau said.
