Tag: incandescent light bulbs

Is there a better way to construct a light bulb? For instance, is there a way to…

Lou Bloomfield Leave a comment

Is there a better way to construct a light bulb? For instance, is there a way to prevent the surface of the bulb from heating so quickly and generating so much heat? Is glass the best cover?

Unfortunately, there is not much that can be done to increase the efficiency of an incandescent bulb. It emits light by creating a very hot filament. Some of the filament’s heat is emitted as visible light but most ends up as hot air or infrared light (which you cannot see). There are tricks used to increase the bulb’s visible light output slightly (e.g. heating the filament hotter as in a halogen bulb or reducing the heat transport in the bulb gas as in a krypton bulb), but mostly there is nothing that can be done. Glass is about the best material for a bulb: it’s clear and a relatively poor conductor of heat.

On a three-way lamp, what are the switch settings for? Does it pump in more ener…

Lou Bloomfield Leave a comment

On a three-way lamp, what are the switch settings for? Does it pump in more energy?

The lamp has four switch positions: off, filament 1 on, filament 2 on, and both filaments on. The bulb has three electrical connections to its filaments. One contact delivers electrical power to filament 1, another contact delivers electrical power to filament 2, and the third contact returns electricity from both filaments to the power plant. The switch carefully controls the flow of electricity to the two filaments so that at the low light setting, only the small filament is on, at the medium setting, only the large filament is on, and at the high setting, both filaments are on.

Which electric light bulb is best for the money, i.e. uses least electricity and…

Lou Bloomfield Leave a comment

Which electric light bulb is best for the money, i.e. uses least electricity and has greatest light. I remember my high school physics teacher saying something like 50 watts -> 100 watts doesn’t double the light, just eats electricity.

For a given type of light bulb, the higher wattage bulbs are more energy efficient. Each light bulb has some “overhead” of wasted power that goes into heating the supporting structure and glass envelope. The higher wattage bulbs produce a little more light per watt of power. But not all types of bulbs are equally efficient. Long life bulbs are the least energy efficient because they run cooler than normal bulbs. The filament lasts a long time, but wastes more power producing infrared light. Some “energy miser” bulbs aren’t as good as normal bulbs. They may have lower wattages (typically 55 W instead of 60 W or 90 W instead of 100 W), but they actually produce significantly less light and thus consume more watts of power for each unit of light they produce. The most efficient incandescent bulbs are halogen lamps. These lamps, with their chemical recycling process, run substantially hotter than normal bulbs and produce more light per watt. They also last longer than normal light bulbs. They also produce whiter light (less red) and are just plain better bulbs than normal light bulbs. They cost more money up front, but it’s worth it in most cases.

Why aren’t you supposed to touch halogen bulbs with your bare hands?

Lou Bloomfield Leave a comment

Why aren’t you supposed to touch halogen bulbs with your bare hands?

When they’re operating, halogen bulbs become extremely hot, so you certainly wouldn’t want to touch them then. But even when a bulb is cool, touching it would deposit greases and salts from your skin onto its surface. The aluminosilicate glass used in the lamp’s envelope would be weakened when these salts are baked into the glass during the lamp’s operation and the greases would scorch and darken the bulb’s surface.