Luminous intensity

Figure 1. A candle has a luminous intensity of about 1 candela, the SI unit of luminous intensity.

Luminous intensity is a measure of the radiant power emitted by an object in a given direction, and is dependent on the wavelength of light being emitted. It is weighted to the sensitivity of the human eye, by what is called the "standard luminosity function". The SI unit for luminous intensity is the candela which has an operational definition, meaning it is defined by a set wavelength of light emitting a specific amount of power.

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