I believe that most modified car owners would pay more attention to lumen and lux of the LED headlight bulb. But it is a big knowledge for ordinary car owner, we perphas don’ know what is lux. It is a big question for me whether the lux of a car light bulb indicates the brightness? Or it means that a bulb is not good? So today I decide to take a brief learning about it. We would hear lux related to a flashlight sometimes. This tells us how light intensity is distributed. It usually measured in the center of the beam. It can be seem that lux is the unit of illuminance and luminous emittance. And it measures luminous flux per unit area.
As lux is a brightness of per unit area. What about lumen? What is the ralation btween them? It is said that a flux of 1000 lumens concentrated into one area of one square metre, lights up with an illuminance of 1000 Lux in that area. The difference between them is that the lux shows the area which the lumens is spread. Light sources with similar lumen ratings, a high lux value indicates spot illumination, and a low one indicates flood illumination.
Now we understand the lux and lumen. But we still do not know the method of measuring lux. Lux is related to lumen. When we measure light, we are interested in how many Lumens fall on a surface. This is what we know as lux. One lux is one lumen per square meter. Take an example, we have a light source produced 1000 lumens. If we could focus this onto the surface of 1 square metre we would have an illuminance of 1000 lux. However if the same light was spread out over 10 square meters, we would only have an illuminance of 100 lux. Lux is concerned to the area where it lights to.