The distance between two consecutive points having the same phase at the same time in the direction of periodic wave propagation. Light and radiation
Light radiates from electromagnetic waves (energy travels from one object to another without the use of any medium). This mode of energy transmission is called radiation) to the human eye, through the optic nerve converted into light, the part of the spectrum that can be seen by the naked eye. Such rays range in wavelength from 360 to 830nm, making them a very small part of the electromagnetic spectrum. The temperature is much higher than the 50Hz operating temperature, resulting in a higher color temperature white color table and better color rendering.
The unit is lumen (lm). All radiant energy emitted by a light source and perceived by the human eye is called luminous flux.
4.Luminous intensity ：
The flux of the light source in a solid Angle in a certain direction. Unit: candela (CD) in general, the light source emits its flux in different directions and with different intensity. The intensity of visible light emitted in a particular direction is called the intensity of light.
Illuminance (Illuminance, E)
5.Unit: Lux (lx) illuminance is the ratio of luminous flux to the illuminated surface. The flux of 1 lumen is evenly distributed in the area of one square meter brightness；
6.Unit: kendra/square meter [CD /m2] brightness (L) is the intensity of light reflected from an object seen by the eye in a certain direction.
Unit: lumens per watt [lm/W] light efficiency refers to the efficiency of converting electrical energy into light energy.
8.Luminance, Luminance, L)
Unit: candela per square meter (CD/square meter) the brightness of a light source or a illuminant refers to the intensity density of the light intensity of the unit surface in a certain direction, which can also be said to be the perceived brightness of the light source or illuminant.
When the color emitted by the light source is the same as the color radiated by the "black body" at a certain temperature, the temperature of the "black body" is called the color temperature of the light source. The higher the temperature of the black body, the more blue and less red components in the spectrum. For example, the light color of an incandescent lamp is warm white with a color temperature of 2700K, while the color temperature of a daylight fluorescent lamp is 6500K.
Light color is actually color temperature. There are three major categories:
Warm color < 3300 k；
The intermediate colors range from 3300 to 5000K and the cool colors are >5000K, 1}. Due to the difference in spectral composition in the light, the color rendering of the lamp may be different even though the light colors are the same.
The efficiency of lamps and lanterns；
Lamp efficiency (also called light output coefficient) is an important standard to measure the energy efficiency of lamps, which is the ratio between the light energy output of lamps and the light energy output of the light source inside lamps.
In principle, artificial light should be the same as natural light, so that the human eye can correctly distinguish the color of things, of course, this depends on the location and purpose of lighting.