Hard to tell without more context. I assume you are talking about critical angles, for total internal reflection (ray coming from side 1 and ##n_1>n_2##)? This is when the angle of refraction reaches 90 degrees and pretty much all the energy is reflected inside the material (I assume n1 > n2). Then we have ##theta_2=90## and you can find the critical angle inside the medium.Sabalaba said:
The main difference between reflected and refracted rays is their direction of travel. Reflected rays bounce off a surface at the same angle as the incident ray, while refracted rays pass through a surface and change direction based on the material they are traveling through.
The critical angle is the angle at which a refracted ray will travel along the surface of a material instead of passing through it. If the incident angle is greater than the critical angle, the refracted ray will be reflected back into the original material.
The critical angle is directly related to the refractive index of a material. The higher the refractive index, the smaller the critical angle, meaning that the material is more likely to reflect a refracted ray rather than allow it to pass through.
Yes, both reflected and refracted rays can exist at the same time. When a beam of light meets the interface between two materials, some of the light will be reflected and some will be refracted, creating both reflected and refracted rays.
The angle of incidence is equal to the angle of reflection for a reflected ray. This is known as the law of reflection and is true for all types of surfaces, whether they are smooth or rough.