Package javax.measure.quantity

Interface LuminousIntensity

  • All Superinterfaces:
    Quantity<LuminousIntensity>
    public interface LuminousIntensity
extends Quantity<LuminousIntensity>
    Luminous flux density per solid angle as measured in a given direction relative to the emitting source. The metric system unit for this quantity is "cd" (candela). The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10¹² Hz, Kcd, to be 683 when expressed in the unit lm W−1, which is equal to cd sr W⁻¹, or cd sr kg⁻¹ m⁻² s³, where the kilogram, metre and second are defined in terms of h, c and ∆νCs. This definition implies the exact relation Kcd = 683 cd sr kg⁻¹ m⁻² s³ for monochromatic radiation of frequency ν = 540 × 10¹² Hz. Inverting this relation gives an exact expression for the candela in terms of the defining constants Kcd, h and ∆νCs: 1 cd = (Kcd / 683) kg m² s⁻³ sr⁻¹
    API Note:
    SI Base Unit
    Since:
    1.0
    Version:
    2.1
    Author:
    Jean-Marie Dautelle, Werner Keil, Thodoris Bais
    See Also:
    Wikipedia: Luminous intensity