The new definition, which took effect on, is: The 26th General Conference on Weights and Measures (CGPM) redefined the candela in 2018. The old name "candle" is still sometimes used, as in foot-candle and the modern definition of candlepower.
If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured. A common wax candle emits light with a luminous intensity of roughly one candela. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the luminosity function, the model of the sensitivity of the human eye to different wavelengths, standardized by the CIE and ISO. It measures luminous power per unit solid angle emitted by a light source in a particular direction. The candela ( / k æ n ˈ d ɛ l ə/ or / k æ n ˈ d iː l ə/ symbol: cd) is the unit of luminous intensity in the International System of Units (SI). The photopic includes the CIE 1931 standard (solid), the Judd–Vos 1978 modified data (dashed), and the Sharpe, Stockman, Jagla & Jägle 2005 data (dotted). Photopic (black) and scotopic (green) luminosity functions.
0 kommentar(er)
