project report on critical agle and total internal reflection of light in a prism
Answers
Introduction
Whenever a ray of incident light travels from one medium to another, its path is changed i.e. it gets refracted.
If the ray travels from denser medium to rarer medium, it suffers deviation away from the normal at the point of incidence. As the angle of incidence is increased, the angle of refraction also keeps on increasing. At a certain angle of incidence, called the critical angle, the refracted ray grazes along the surface of separation i.e. angle of refraction becomes just go. If the angle of incidence is further increased, no refraction takes place. Instead such a ray gets reflection inside the medium itself. This phenomenon is called total internal reflection.
Refraction :
The phenomenon of bending of light when it come from one medium to another medium is called refraction.
Reflection :
The phenomenon in which a ray comes from one medium and bending of that ray in same medium i.e. Total Internal Reflection takes place called reflection.
Total Internal Reflection
Total internal reflection is the phenomenon of reflection of light which occurs when a ray of light traveling in a denser medium is incident at the interfere of the two media at an angle greater than the critical angle for that pair of media.
Consider a surface xy separates the rarer medium a from the denser medium b. A ray of light OA from the object O in denser medium incident normally on the surface of separation, gets refracted into the rarer medium as such along AL. Another ray of light incident along the oblique path OA, is refracted away from normal along the path A1B1 in rarer medium. As the angle of incidence is increased, the angle of refraction also goes on increasing, till for a certain angle of incidence C, called the critical angle. When angle of incidence is greater than critical angle then total internal reflection takes place.
Conditions for Total Internal Reflection
1. The ray incident on the interface should travel in optically denser medium.
2. The angle of incidence should be greater than the critical angle for the given pair of media.
Introduction
Relation between refractive index (m) and critical angle (C)
When refraction takes place at point C, it follows that the refractive index of medium a w.r.t. medium b is given by
bma =
amb = if i = c (critical angle)
r = 90o
amb =
Refractive index is inversely proportional to sin of critical angle.
Its relation with polarizing angle :
According to Brewster’s Law, when light is incident at polarizing angle at the interface of a refracting medium, the refractive index of the medium is equal to the tengent of the polarizing angle.
If P is polarizing angle and u, the refractive index of the refracting medium, then u = tan P.