one kindOptical phenomenon。It refers to the phenomenon that when light travels to different substances, it changes the propagation direction on the interface and returns to the original substance.Light will reflect when it meets the surface of water, glass and many other objects.When light changes its propagation direction on the interface between two substances and returns to the original substance, it is calledReflection of light。
Reflected lightAndIncident light、normalOn the same plane;The reflected light and the incident light are separated on both sides of the normal;Reflection anglebe equal toAngle of incidence。It can be summarized as: "Three linesCoplanar, two lines live apart, and two corners are equal ".Light hasreversibility。In the phenomenon of light reflection, the light path is reversible.
The phenomenon that light changes its propagation direction on the interface between two substances and returns to the original substance is calledReflection of light。
Laws of physics
1. In reflection, reflected light, incident light andnormalAll in the same plane;
(It can be summarized as: "three lines are coplanar, two lines live apart, and two angles are equal".)
The reflection angle changes when passing from one medium to another.
reflectivity
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reflectivity, also known asReflective ability, is reflectionlight intensityDegree andincident lightThe ratio of strength.The surfaces of different materials have different reflectivity, and the values are mostlypercentageIt means that the same material can have different reflectivity to light of different wavelengths. This phenomenon is calledSelect Reflection。So if you list the reflectivity of a materialShould beIndicate its wavelength, for example, glass withvisible lightThe reflectivity of gold is about 4%. The selectivity of gold is very strong. The reflectivity near the green light is 50% and the reflectivity to the infrared light is more than 96%. In addition, the reflectivity is also related to the medium around the reflective material and the incident angle of light.The above refers to the reflectivity of light at the interface between each material and air, and is limited toNormal incidenceThe situation.
total reflection
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Light consists of light densitypropagation velocitySmaller)mediumIt refers to the phenomenon that when it hits the interface of the light sparse medium (i.e. the medium in which light travels at a high speed), it is completely reflected back into the original medium.
When light strikes the interface of two media, only reflection will occur without refractionOptically dense mediumShooting directionOptically sparse mediumWhen,Refraction angleIt will be greater than the incidence angle. When the incidence angle increases to a certain value, the refraction angle will reach 90 °, which will not appear in the light sparse mediumRefraction ray, no longer exists as long as the incidence angle is greater than the above valueRefraction phenomenon, this istotal reflectionTherefore, the conditions for generating total reflection are: ① light must be emitted from the dense medium to the sparse medium; ② the incidence angle must be greater thancritical angle．
The critical angle is the corresponding incident angle when the refraction angle is 90 degrees (total reflection will occur only when the light enters the light sparse medium from the light dense medium and the incident angle is greater than the critical angle)
