Suppose I have a lamp that gives y Lux light.
I buy an identical lamp and put it right next to it.
Do I now have 2y Lux light?
For example, how do you convert Lux to Candela?
Or how different light units?
Answer
Indeed, 2 lamps of 1 lux is a total of 2 lux. The physiological unit “lux” (lx) is equivalent to the physical unit “W/m2”. Similarly, the physiological unit “candela” (cd) is equivalent to the physical unit “watt” (W).
The cd stands (just like W) for the total amount of light emitted (light energy) by a light source, whereby the amount of light is thought to be homogeneously spread over an angle of 1 “steradial” (SR) instead of in all directions. 1 sterad = a cone with a point of 1 radian = about 57 degrees = total sphere / 4.PI.
The real equivalent of Watts is lumens (lm). The total light energy emitted by the lamp is expressed in “lumens” (lm). So 1cd = 1lm/sr. Note: The ratio 1cd=1lm/4PI is only valid for a lamp emitting perfectly spherical symmetrical.
The light source irradiates per unit area in “lx”, and the ratio is “1lx = 1 lumen/m2.
Lumen stands to W like lux to W/m2 and candela to W/SR.
If you radiate 1 lumen in a cone of approx. 57 degrees (1 SR) that is 1 candela.
Converting from candela to lux: a light source of 1 candela irradiates an object 1m away with 1lx.
If the object is further or closer, this value is inversely proportional to the square of the distance: illuminance [lx] = luminosity [cd] / distance^2 [m2]
Answered by
Engineer Bart Dierickx
electronics imagers cryogenics metaphysical questions aerospace and the most impossible things
http://electroniade.org/
.