In Soviet times, choosing a light bulb, consumerswere guided by the number of watts in it. The more of them - the brighter the light of this device. However, today (when many new varieties of lamps have appeared on store shelves) it is increasingly necessary to come across such a concept as “lumen”. What is it, what is different from a watt, and what unit is called a lumen per watt? Let's find the answers to these questions.
What is lumen?
In the middle of the twentieth century. To avoid confusion in units of measurement between different countries, a universal SI system was introduced. Thanks to her, we have watts, amps, meters, kilograms, etc.
According to it, the unit of measurement of the luminous flux (visible electromagnetic radiation) is the lumen (lumen). In fact, in these units measure the amount of light emanating from its source.
Also on the question of what is “lumen, you canreply that this is the name of a famous Russian rock band from Ufa. Having started its activity in 1998, for almost twenty years it has continued to be loved by many listeners in the Russian Federation and abroad.
Origin of the word
Having learned what lumen is, it is worth clarifying where the word came from in the Russian language.
Like most names of units of measurement in the SI system, the term in question is Latinism. It is derived from the word "light" (lūmen).
Some linguists claim that the noun could also be derived from the Proto-Indo-European word leuk (white) or from lucmen (meaning not precisely established).
What makes lumen different from luxury
Considering the meaning of the word "lumen", it is worth mentioning such a close concept as "luxury".
Both of these terms refer to lightenergy units, however, the lumen is all the light emitted by the source, and lux is the amount that reached the illuminated surface, and was not stopped by any obstacles with the formation of shadows.
The interdependence of these units can be reflected with the following formula: 1 lux = 1 lumen / 1 square meter.
For example, if a lamp illuminating a territory of 1 m2emits 50 lumens, then the illumination of this place is 50 lux (50 lm / 1m2 = 50 lx).
However, if the same lamp with the same amount of light is used to be placed at 10 m2, then the illumination in it will be less than in the previous case. Only 5 suites (50lm / 10m2 = 5 lx).
In addition, such calculations did not take into account the presence of various obstacles that impede the attainment of light rays from the surface, which significantly reduces the level of illumination.
Due to this situation in any country of the worldThere are norms of illumination for various buildings. If it is lower than them, the person’s vision lacks light and deteriorates. For this reason, having decided to make repairs or rearrangement in your home, it is always important to take into account this nuance.
There are also a number of design programs in which such calculations are made automatically.
Lumen and watt
Having learned the difference and the value of lumen and lux, one should pay attention to another SI unit - watts.
Due to the fact that they are used to measure the power of light bulbs, some believe that it is possible to relate these units to one another freely. However, this is not quite true.
The fact is that in watts the power of the energy consumed by the light bulb is measured, and in lumens the amount of light it emits.
During the existence of incandescent lamps onlyit was easier to calculate the amount of light from such a device. Since the 100 watt light bulb gave out about 1600 lm of light. While a similar device in 60 W - 800 lm. It turned out, the more energy consumed - the better the lighting.
But today is not the case.In recent decades, several new types of light sources have been invented (LED lamps, fluorescent lamps, etc.). Their advantage is cost effectiveness. That is, they shine brighter with a smaller amount of energy used.
In this regard, if necessary, to make the relationship between watts and lumens, you need to take into account the type of lamp and look for its luminosity in special tables.
Стоит отметить, что обычному человеку иногда не I want to rebuild and understand all these subtleties. Therefore, the majority of domestic manufacturers of new-type light bulbs on the labels indicate not only the number of lumens, but how much less watts this device consumes (compared to incandescent bulbs). For example: a 12 watt lamp gives out light as at 75 watts.
Unit of measurement "lumen per watt": its value and scope
Although watts and lumens are differentcategories, together they are a measure of the light output of the device. Lm / W is an indicator of the efficiency of the light source. That is, how much energy it consumes and how much light it emits at its expense.
For example, a 40-watt incandescent lamp has a light output of 10.4 lm / W. At the same time, for an induction bulb with the same power, this indicator is much higher - 90 lm / W.
For this reason, choosing a lighting device in the house, you should still not be too lazy, but find out the level of its light output. As a rule, such data is on the labels.
