What Is a Candela?
Candela is a unit of luminous intensity, one of the 7 basic units of the International System of Units (SI). Referred to as "kan", symbol cd. It is the luminous intensity of a light source in a given direction. The light source emits monochromatic radiation with a frequency of 540 × 10 ^ 12 Hz, and the radiation intensity in this direction is 1/683 watts / sphericity.
- [kn dé l]
- Candela is
- Luminous intensity is referred to as light intensity, and the international unit is (Candela) abbreviated cd. 1cd refers to the luminous flux emitted by the light source within a unit solid angle in a specified direction. When the light source radiation is uniform, the light intensity is I = F / , is the solid angle, the unit is spherical degree (sr), F is the luminous flux, and the unit is lumen. For point light sources, I = F / 4. Luminance refers to the brightness of the luminous surface, and refers to the ratio of the luminous intensity of the luminous surface in the specified direction to the area of the luminous surface that is vertical and in the specified direction. For a diffuse scattering surface, although the light intensity and luminous flux in each direction are different, the brightness in each direction is equal. The fluorescent screen of a television is similar to such a diffuse scattering surface, so when viewing images from all directions, they have the same brightness.
- The unit of luminous intensity was originally defined with candles, the unit is candlelight. Ninth in 1948
- The following are the brightness values of some light sources (unit cd / )
- Sun: 1.5E + 9 [1]
- 1cd / m 2 = 1 / 10000cd / cm 2