what is lumen ofphyshics?.
Answers
Explanation:
The Lumen
The lumen is the standard unit for the luminous flux of a light source. It is an SI derived unit based on the candela. It can be defined as the luminous flux emitted into unit solid angle (1 sr) by an isotropic point source having a luminous intensity of 1 candela. The unit lumen is then equal to cd x sr. The abbreviation is lm and the symbol is Φv. In terms of radiant power (also called radiant flux) it can be expressed as:
Luminous flux in lumens = Radiant power (watts) x 683 lumens/watt x luminous efficacy
The luminous flux is the part of the power which is perceived as light by the human eye, and the figure 683 lumens/watt is based upon the sensitivity of the eye at 555 nm, the peak efficiency of the photopic (daylight) vision curve. The luminous efficacy is 1 at that frequency.
A typical 100 watt incandescent bulb has a luminous flux of about 1700 lumens.
Units for other quantities in photometry contain the lumen, such as the lux (lumens/meter2)