Luminous intensity is a measure of the energy emitted by a light source in a particular direction.

The SI unit of Luminous intensity is the candela (cd).

1 cd is that luminous intensity emitted by a monochromatic light source of frequency 540 × 10¹² hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

SI light units edit  (http://www.wordiq.com/definition/Template:SI_light_units)
Quantity	SI unit	Symbol	Notes
Luminous energy	joule	J
Luminous flux	lumen or ( candela · steradian )	lm	also called Luminous power
Luminous intensity	candela	cd
Luminance	candela / square metre	cd/m2	also called Luminosity
Illuminance	lux or (lumen / square metre)	lx
Luminous efficacy	lumens per watt	lm/w

See also

• Intensity

fr:Intensité lumineuse it:Intensità luminosa nl:Lichtsterkte