Types
Types of electric lighting include:
- incandescent light bulbs
- arc lamps
- gas discharge lamps, e.g., fluorescent lights and compact fluorescent lamps, neon lamps, flood lamps, modern photographic flashes
- lasers
- light-emitting diodes, including OLEDs
- sulfur lamps
Different types of lights have vastly differing efficiencies and color of light.
| Name | Optical spectrum | Nominal efficiency (lm/W) |
Lifetime (MTTF) (hours) |
Color temperature (kelvin) |
Color | Color rendering index |
|---|---|---|---|---|---|---|
| Incandescent light bulb | Continuous | 4-17 | 2-20000 | 2400-3400 | Warm white (yellowish) | 100 |
| Halogen lamp | Continuous | 16-23 | 3000-6000 | 3200 | Warm white (yellowish) | 100 |
| Fluorescent lamp | Mercury line + Phosphor | 52-100 (white) | 8000-20000 | 2700-5000* | White( various color temperatures), as well as saturated colors available | 15-85 |
| Metal halide lamp | Quasi-continuous | 50-115 | 6000-20000 | 3000-4500 | Cold white | 65-93 |
| Sulfur lamp | Continuous | 80-110 | 15000-20000 | 6000 | Pale green | 79 |
| High pressure sodium | Broadband | 55-140 | 10000-40000 | 1800-2200* | Pinkish orange | 0-70 |
| Low pressure sodium | Narrow line | 100-200 | 18000-20000 | 1800* | Yellow, no color rendering | 0 |
| Light emitting diode | Line plus phosphor | 10-110 (white) | 50,000-100,000 | Various white from 2700 to 6000* | Various color temperatures, as well as saturated colors | 70-85 (white) |
*
The most efficient source of electric light is the low-pressure sodium lamp. It produces, for all practical purposes, a monochromatic orange/yellow light, which gives a similarly monochromatic perceprtion of any illuminated scene. For this reason, it is generally reserved for outdoor public lighting usages. Low-pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be easily filtered, contrary to broadband or continuous spectra.
Read more about this topic: Electric Light
Famous quotes containing the word types:
“Our children evaluate themselves based on the opinions we have of them. When we use harsh words, biting comments, and a sarcastic tone of voice, we plant the seeds of self-doubt in their developing minds.... Children who receive a steady diet of these types of messages end up feeling powerless, inadequate, and unimportant. They start to believe that they are bad, and that they can never do enough.”
—Stephanie Martson (20th century)
“... there are two types of happiness and I have chosen that of the murderers. For I am happy. There was a time when I thought I had reached the limit of distress. Beyond that limit, there is a sterile and magnificent happiness.”
—Albert Camus (1913–1960)
“The wider the range of possibilities we offer children, the more intense will be their motivations and the richer their experiences. We must widen the range of topics and goals, the types of situations we offer and their degree of structure, the kinds and combinations of resources and materials, and the possible interactions with things, peers, and adults.”
—Loris Malaguzzi (1920–1994)