As mentioned, the resulting change of the direction of a wave when it strikes on any obstacle is called reflection. When it apply to light rays, reflection occurs when light strikes on shiny polished surfaces (reflective media).The reflection undergoes two simple geometrical rules; the incident ray, the normal, and the reflected ray are all lie in the same plane and the angle of incidence is equal to the angle of reflection. Here incident ray is defined as a ray approaching to the surface. Point of incident is the place where the incident ray strikes the surface. The normal is the line drawn perpendicular to the surface at the point of incidence. The reflected ray is the portion of incidence ray that leaves the surface at the point of incidence. There are two kinds of light reflections, which are called specular reflection and diffuse reflection. Specular reflection occurs when parallel rays of incidence strike on a smooth surface reflecting parallel, and diffuse reflection occurs when the parallel incident rays strikes on a rough surface reflecting irregularly to all directions due to the uneven planes on the surface.
Total internal reflection
If and only when, light rays pass through a denser medium to a lighter medium, or in other words, through a medium with a high refractive index (n1) to a low refractive index (n2) medium (n1 > n2) and incident angle is larger than the critical angle, result a total reflection of the incident ray without passing through to the lighter medium. Here critical angle is defined as the incident angle, which makes a refracted angle of 90 degrees. This concept is used in fiber optics to reach information at a short period of time and to get bright sparkle diamonds, are cut in order to use this phenomena.
What is the difference between Reflection and Total Internal Reflection?
· Reflection and total internal reflection are physical properties of waves. Reflection occurs in all kind of waves, but total internal reflection occurs only with light rays.
· Total internal reflection occurs when light passes through denser medium to the lighter medium. But for reflection there is no such restriction to consider.
· In reflection of a wave, both reflection and refraction (passing through second medium) waves occur. But in total internal reflection, only reflection ray is occurs.
· In total internal reflection, energy of incident ray and reflected ray are equal. However, in reflection it does not.