fényáramot

Fényáramot, often translated as luminous flux, is a measure of the total amount of visible light emitted by a source per unit time. It quantifies the perceived brightness of a light source, taking into account how sensitive the human eye is to different wavelengths of light. The standard unit of luminous flux is the lumen (lm).

The concept of luminous flux is distinct from radiant flux, which measures the total energy of electromagnetic radiation emitted by a source, regardless of whether it is visible to humans. Luminous flux is specifically concerned with the visible spectrum and is weighted by the luminosity function, which represents the average spectral sensitivity of human visual perception. This means that light with wavelengths that the human eye perceives as brighter will contribute more to the luminous flux than light of the same radiant energy but at less visible wavelengths.

For example, a light source emitting 100 watts of infrared radiation will have a high radiant flux but a very low luminous flux because infrared light is invisible. Conversely, a light source emitting 100 watts of green light, which is highly visible to the human eye, will have a significantly higher luminous flux. The luminous flux of a light source is a key specification used in lighting design and in comparing the efficiency of different light bulbs. Higher luminous flux generally indicates a brighter light source.