The law of refraction was discovered by the Dutch mathematician Snitch, which is the law to determine the direction of refracted light in the phenomenon of light refraction. The refracted ray lies in the plane determined by the incident ray and the normal of the interface; Refracted light and incident light are on both sides of the normal respectively; For two kinds of media with certain refractive index, the ratio of sine of incident angle I to sine of refraction angle I' is constant.

The formula of refraction law is one of the basic laws of geometric optics, which determines the relationship between the propagation direction of incident light and refracted light when light refracts through the interface between two media. As shown in the figure, the plane formed by the incident light and the interface normal passing through the incident point is called the incident plane, and the included angles between the incident light and the refracted light and the normal are called the incident angle and the refraction angle respectively, which are expressed as θ 1 and θ2 respectively.

The law of refraction is expressed as follows: ① The refracted light is in the incident plane. (2) The ratio of sine of incident angle to refraction angle is constant, which is expressed by n2 1

sinθ 1/sinθ2=n2 1

Where n2 1 is called the relative refractive index of the second medium to the first medium.

Or sinθ1* n1= sinθ 2 * N2.

Law of refraction of light 1. Refraction of light: when light is injected from one medium into another, the phenomenon that the propagation direction of light changes at the interface between the two media is called refraction of light.

2. The refraction law of light: the refracted ray, the incident ray and the normal are in the same plane, and the refracted ray and the incident ray are separated on both sides of the normal; The sine of the incident angle is proportional to the sine of the refraction angle.

3. In the refraction phenomenon, the optical path is reversible.