The concept of light
Radiation: the phenomenon of emission or transmission of energy by electromagnetic waves or particles, which can cause visual radiation only through the visual organ.
: light is an electromagnetic wave propagation, the form of light source can be people's eyes felt by electromagnetic wave, the wavelength range of 380 nm 780 nm ∽ (nm:
-9 nanometer, length unit 1nm = 10m), longer than 780nm for infrared, radio and so on, short of 380nm for ultraviolet ray, X-ray, cosmic ray and so on.
Visible part and decomposable ChengGongGuang (780 nm 620 nm) ∽, orange light (620 nm ∽ 590 nm), yellow (590 - nm ∽ 560 nm), green (560 nm 500 nm) ∽, green light (500 nm 470 nm) ∽, blu-ray (470 nm 430 nm) ∽, purple light (430 nm 380 nm) ∽ seven basic including monochromatic light.
Like all other electromagnetic radiation, light travels in a straight line at 300,000 kilometers per second in a vacuum.When light passes through a substance, such as water or air, it travels slower.The ratio of the speed of light in a vacuum to the velocity in the medium is called the refractive index of the medium.In the interface of two kinds of media with different refractive index, the incident light is refracted and launched.In addition, scattering, diffuse reflection, diffuse transmission and so on are also generated during propagation.
Luminescence: the object absorbs the energy of light, electricity, radiation and so on, and then emits energy in the form of light.
Luminescence is divided into: laser light (laser), field emission (display), gas discharge luminescence (gold halide lamp), photoluminescence (fluorescent lamp),
Radiant luminescence (incandescent lamp, halogen lamp), cathode luminescence (picture tube)