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Guide
1
According to the definition, the lighting in one suite creates a light source with a luminous flux of one lumen uniformly illuminates if the surface area of ​​one square meter.Therefore, for the transfer lumen in the suites can use the formula:

Klyuks = Klum / km²

To translate suites in lumens, apply the formula:

Klum = Klyuks * km²,


where:
Klyuks - lighting (the number of lux);
Klum - the luminous flux (lumen output);
km² - illuminated area (in square meters).
2
The calculations take into account that the coverage should be uniform.In practice this
means that all points of the surface must be equidistant from the light source.Thus, light should be incident on the surface at all portions of the same angle.Also note that the surface has to fit all the emitted light source luminous flux.
3
If the light source is similar in shape to a point, the uniform illumination can be achieved only on the inner surface of the sphere.However, if the lamp is sufficiently far from the illuminated surface, and the surface itself is relatively flat and has a small area, the illumination can be considered practically uniform."Striking" example of such a light source can be regarded as the sun, which due to the vast distances is almost a point source of light.
4
Example: In the center of a cubic room 10 meters high is located incandescent lamp 100 watts.

question: what will be the illumination of the ceiling of the room?

Solution: incandescent lamp 100 watts creates a luminous flux of approximately equal to 1300 lumens (lm).This stream is divided into six equal surfaces (walls, floor and ceiling) with a total area of ​​600 m².Hence their coverage (average) will be: 1300/600 = 2,167 lux.Accordingly, the average illumination of the ceiling will also be equal to 2,167 lux.
5
To solve the inverse problem (determination of the luminous flux at a given surface area and lighting) simply multiply the illumination of the area.
6
In practice, however, the luminous flux generated by the light source, so is not calculated and measured by means of special devices - spherical photometers and photometric goniometer.But since most of the lights are standard features, then for practical calculations use the following table:

Bulb 60W (220) - 500 lumens.
Incandescent 100 W (220) - 1300 lm.
Fluorescent lamp 26 W (220) - 1600 lm.
sodium-vapor lamp (street) - 10000 ... 20000 lm.
low-pressure sodium lamps - 200 lumens / watt.
LEDs - about 100 lm / W.
Sun - 3.8 * 10 ^ 28 lm.
7
lm / W - an indicator of the efficiency of the light source.For example, the LED 5 Watt provide a luminous flux of 500 lumens.That corresponds to an incandescent bulb, the power consumption of 60 watts!