It sometimes appears resonance phenomenon that both the reflective wave and refractive wave coexist when the incident angle is a value of the range for wave through the interface for example both air and water. We design a kind of calculation method of resonance wave reflectivity on the basis of the degree of the ratio of both the normal component of incident wave the wavelength that is compressed and refractive wavelength when incident wave the through the interface. The methods could calculate resonance phenomenon that the wave travel to split into two ray direction on the interface both sides. The methods will be widely used in various fields for resonance wave calculation such as light, electromagnetic waves, sound waves and water waves etc.
This article is in connection with calculating of reflection critical angle on interface, author has found that reflective wave have a quarter wavelength effects and deduced both absolute and relative reflection critical Angle calculation formulas. The two formulas can easy solve the question of reflection critical angle on interface of one side of the air where it is not calculated by Snell’s law. Snell’s law only reveals that rate of the wave velocity projected to the interface, the methods of this paper reveal the normal component of wave velocity on the interface relationship. The methods will be widely used in various fields such as light, electromagnetic waves, sound waves and water waves etc.