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
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