Candela (cd) - definition
Candela (cd) - definition
Candela (cd) is the SI base unit of luminous intensity, used to quantify the perceived brightness of light emitted by a source in a given direction. It represents the amount of visible light, as perceived by the human eye, emitted by a source with a defined radiation characteristic. The definition of the candela is based on the emission of monochromatic electromagnetic radiation at a frequency of 540 × 10¹² Hz with a radiant intensity of 1/683 watt per steradian, corresponding to green light, to which the human eye is most sensitive.
This unit is used to quantitatively describe the photometric properties of light sources, regardless of their design or operating principle. The candela takes into account not only the physical power of radiation but also the subjective sensitivity of human vision, making it one of the fundamental quantities in photometry. A value expressed in candelas allows for the comparison of brightness between different light sources and the analysis of their impact on lighting conditions in a given space.
In technical applications, the candela refers to directional luminous intensity—i.e., the ability of a source to concentrate its emission in a specific direction. This is crucial in the design of task lighting, reflectors, automotive lamps, traffic signals, and measurement devices. In lighting engineering, values expressed in candelas enable precise determination of light distribution in space and adjustment of lighting systems to meet functional and regulatory requirements.
The candela is closely related to other photometric units such as the [lumen (luminous flux)(/ca/en/news/library-articles/page/69180/) and lux (illuminance), enabling comprehensive characterization of light properties in terms of their environmental effects and visual perception.
Transfer Multisort Elektronik (TME) is one of the world’s largest global distributors of electronic components, electrotechnical parts, workshop equipment, and industrial automation. The catalog includes over 1,500,000 products from 1,300 leading manufacturers. TME’s modern logistics centers in Łódź and Rzgów (Poland), with a combined area of over 40,000 m², ship nearly 6,000 packages daily to customers in more than 150 countries.
TME also invests in the development of knowledge and skills of young engineers and electronics enthusiasts through the TME Education project, and supports the tech community by organizing the TechMasterEvent series, promoting innovation and experience exchange.
