Science Fair Project Encyclopedia
Lumen (unit)
In physics, specifically photometry (optics), the lumen (symbol: lm) is the SI derived unit of luminous flux. It is the amount of light that falls on a unit area at unit distance from a source of one candela. A 100 watt incandescent light bulb will output around 1400 lumens.
Efficiency
The efficiency of a lamp can be expressed in lumens per watt. In general, a higher-powered lamp will be more efficient, so that a 100W bulb will produce more lumination per unit of power than a 60W bulb of the same type.
| Lamp type | Lumens per watt |
|---|---|
| Incandescent light bulb | 11-16 |
| Compact fluorescent | 50-70 |
| Metal halide lamp | 80-120 |
| Sodium vapor lamp | 90-150 |
SI light units
Last updated: 06-02-2005 13:08:33
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details