TOTAL INTERNAL REFLECTION&

ITS APPLICATIONS

Presented by

Chithra V M Physical Science GCTE Thycaud

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

Bending of light takes place when light passes obliquely from one

transparent medium to another.

• When light ray enters from a denser medium to a rarer medium it bends away from the normal

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

• When angle of incidence becomes greater than critical angle the incident ray is totally reflected

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

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

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

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

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