When light encounters a boundary between two transparent mediums, such as air and glass, both reflection and refraction can occur simultaneously due to the interaction between the incident light wave and the atoms or molecules of the medium.
Reflection occurs when the incident light wave "bounces off" the boundary and returns to the original medium. This phenomenon follows the law of reflection, which states that the angle of incidence (the angle between the incident ray and the normal to the boundary) is equal to the angle of reflection (the angle between the reflected ray and the normal).
Refraction, on the other hand, happens when the incident light wave crosses the boundary and enters the second medium. The change in the speed of light as it transitions from one medium to another causes the light wave to change direction. This change in direction is determined by Snell's law, which relates the angle of incidence and the angle of refraction to the indices of refraction of the two mediums.
Now, regarding polarization, light is an electromagnetic wave consisting of oscillating electric and magnetic fields perpendicular to each other. When light is incident upon a surface, the electric field component can interact with the charged particles (electrons) in the material, causing them to oscillate as well.
The reflected light wave is polarized because the oscillation of the electrons in the material preferentially absorbs and re-emits light waves that are oscillating in a specific direction. This selective absorption and re-emission process is influenced by the orientation of the incident electric field with respect to the crystal structure of the material. As a result, the reflected light is polarized parallel to the plane of incidence.
The transmitted (refracted) light wave also experiences a change in polarization, but it is influenced by both the incident polarization and the angle of incidence. The transmitted light wave can be partially or fully polarized depending on the angle and the properties of the material.
In summary, when light interacts with a boundary between two transparent mediums, both reflection and refraction can occur simultaneously due to the interaction of the light wave with the atoms or molecules in the medium. The reflected component is polarized parallel to the plane of incidence due to the selective absorption and re-emission of light waves by the material's electrons, while the transmitted component may also experience a change in polarization depending on the angle and properties of the medium.