Definition:Lumen

Definition

The lumen is the SI unit of luminous flux.

It is defined as being the amount of light emitted in $1$ second into a solid angle of $1$ steradian by a uniform point source with a luminous intensity of $1$ candela:

$1 \, \mathrm {lm} = 1 \ \mathrm {cd} \, \mathrm {sr}$

Symbol

$\mathrm {lm}$

The symbol for the lumen is $\mathrm {lm}$.

Its $\LaTeX$ code is \mathrm {lm} .

Base Units

The SI base units of the lumen are:

$\mathrm {lm} := \mathrm {cd} \, \mathrm {sr}$

where:

$\mathrm {cd}$ denotes candelas

$\mathrm {sr}$ denotes steradians.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): lumen
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): lumen