Luxury and lumens very often confuse. These sizes are used for measurement of illumination and a light stream, respectively, and it is necessary to distinguish them. The size of a light stream characterizes a light source, and illumination level – a condition of a surface on which light gets. For measurement of illumination the unit of measure luxury (Lx) is used, and the lumen (Lm) is applied to characteristic of a light source.
It is required to you
- - calculator.
Instruction
1. According to definition, illumination in one luxury creates source light with a light stream in one lumen if it evenly lights a surface of one square meter. Therefore, for transfer of lumens to luxury use a formula: Klux = Klyumen/Km²Чтобы to transfer luxury to lumens, apply a formula: Klyumen = Klux * Km², where: Klux – illumination (quantity luxury); Klyumen – the size of a light stream (quantity lumen); Km² - the lit area (in square meters).
2. When calculating consider that lighting has to be uniform. In practice it means that all points of a surface have to be equidistanted from a light source. At the same time, light has to get on all sites of a surface under the same corner. Also consider that on a surface all light stream radiated by a light source has to get.
3. If the light source is close in a form to dot, then uniform lighting can achieve only on the internal surface of the sphere. However, if the lamp is rather removed from the lit surface, and the surface rather equal and has the small area, then illumination can be considered almost uniform. The "bright" example of a similar light source can be considered the sun which due to huge remoteness is almost dot light source.
4. Example: In the center of the cubic room 10 meters high the 100 W glow lamp is located. Question: what will be room ceiling illumination? Decision: the 100 Watts glow lamp creates a light stream approximately equal 1300 lumen (Lm). This stream is distributed on six equal surfaces (walls, a floor and a ceiling) with a total area of 600 m². Therefore their illumination (average) will be: 1300 / 600 = 2.167 Lx. Respectively, the average illumination of a ceiling will be also equal 2.167 Lx.
5. For the solution of the return task (definition of a light stream at the set illumination and surface area) just increase illumination by the square.
6. However in practice, the light stream created by a light source so does not pay off, and is measured by means of special devices – spherical photometers and photometric goniometers. But as the majority of light sources have standard characteristics, for practical calculations use the following table: The glow lamp of 60 W (220 V) – 500 Lm. The glow lamp of 100 W (220 V) – 1300 Lm. The fluorescent lamp of 26 W (220 V) - 1600 Lm. A sodium gas-discharge lamp (street) - 10000...20000 Lm. Sodium lamps of low pressure - 200 Lm/Tue. Light-emitting diodes – about 100 Lm/Tue. The sun – 3.8 * 10^28 Lm.
7. Lm/W – an indicator of efficiency of a light source. So, for example, the 5 W light-emitting diode will provide a light stream in 500 Lm. What corresponds to the glow lamp consuming the power of 60 W!