This document discusses total internal reflection and its applications. Total internal reflection occurs when light travels from an optically denser medium to a less dense medium at an angle greater than the critical angle, causing the entire light ray to be reflected back into the denser medium. This phenomenon is used in applications like mirages, optical fibers, and cutting diamonds to maximize their brilliance. Optical fibers use total internal reflection to transmit light along their length, and the facet cuts of diamonds are designed to produce total internal reflection and make the diamond sparkle.
2. Optical density
Ability of a medium to refract light
Two types of medium-rarer medium and denser medium
Rarer medium has lower refractive index
Denser medium has higher refractive index
Speed of light is higher in rarer medium than in denser
medium
3. Bending of light takes place when light passes obliquely from one
transparent medium to another.
4. When light ray enters from a denser medium to a rarer medium it
bends away from the normal
5. As angle of incidence (i) increases so does the angle of refraction
At a particular angle of incidence the angle of reflection becomes 900
Refracted ray grazes the surface at the interface between the two media
The angle of incidence for which angle of refraction becomes 900
CRITICAL ANGLE
6. When angle of incidence becomes greater than critical angle the
incident ray is totally reflected
7. Total internal reflection
When a ray of light travels from denser medium to rarer medium ,if
the angle of incidence is greater than the critical angle the entire ray
is reflected into the same medium by obeying the laws of reflection .
Conditions for total internal reflection
Light must travel from denser medium to rarer medium
The angle of incidence must be greater than the critical angle
9. Mirage
The optical illusion due to total
internal reflection
On sunny days the air near the
ground is cooler than that
higher up
The light rays curve
downward, producing a
superior image
10. Optical fiber
Thin hair like structure
Light enters one end of the wall of the fiber
strikes at less than critical angle
Light undergoes repeated total internal reflection
Light emerges through the other end of fiber
11. Diamond
The critical angle of diamond is very small
The cut of diamond favors total internal
reflection
Rays entering the top of diamond reflects
internally