Yes, the lumen (lm) is an SI derived unit.
The lumen is the SI derived unit of luminous flux, a measure of the total amount of visible light emitted by a source. It quantifies the "amount" of visible light in terms of human perception. In simpler terms, it tells us how bright a light source appears to our eyes.
Here's a breakdown:
- SI Base Units: The International System of Units (SI) has seven base units (e.g., meter, kilogram, second, ampere, kelvin, mole, candela).
- SI Derived Units: These are units derived from the seven SI base units. They are formed by multiplying or dividing base units. The lumen falls into this category.
The lumen is derived from the candela (cd), which is the SI base unit of luminous intensity. Specifically, 1 lumen is defined as the luminous flux emitted per unit solid angle by a point source having a luminous intensity of 1 candela radiating uniformly in all directions.
Therefore, because the lumen is derived from the candela (an SI base unit), it's correctly classified as an SI derived unit.
