The luminous efficiency is a measure that indicates how efficient a light source is. It is the ratio of lumens to power or watts, so it is measured in lumen per watt (lm/W) in the International System of Units. The higher the value, the more efficient a light source is.
Exemplary lumen values:
|
Fluorescent tube (48 Watt) |
3000 lm |
|
Energy-saving lamp (23 Watt) |
1400 lm |
|
Light bulb (100 Watt) |
1340 lm |
|
Candle |
12 lm |
Examples of luminous efficiency of different lamps:
|
Incandescent lamps |
6 – 19 lm/W |
|
Halogen lamps |
13 – 23 lm/W |
|
Fluorescent lamps |
52 – 85 lm/W |
|
High-pressure mercury vapor lamps |
40 – 58 lm/W |
|
High-pressure sodium vapor lamps |
70 – 140 lm/W |
What is light intensity? (Candela definition)
The luminous intensity is a photometric value that describes the radiation of light emitted in a certain direction. Since the radiation behavior of an optical signaling device is not only determined by the light source but also by the design of the domes, the luminous intensity is best suited to characterize the signaling effect of optical signaling devices.
Light intensity is one of the photometric quantities. It relates the light flux to the beam angle of a light source. The luminous intensity therefore indicates how concentrated the light is or what density the emitted light has.
What is the metric unit used for measuring luminous intensity? Candela (cd) is the metric unit of luminous intensity. As an example, the luminous intensity of a candle is approximately one candela.
Post time: Aug-03-2022