TOTAL INTERNAL REFLECTION
Phenomena based on Total internal reflection
SCATTERING OF LIGHT
Law of Refraction
The incident ray, the refracted ray and normal at the point of incidence all lie in the same plane.
The ration of sine of angle of incidence to the sine of the angle of refraction for a given medium is a constant. The constant is equal to refractive index of second medium w.r.t. first medium.
Refraction Phenomena
Difference between Refraction and Reflection.
Reflection is when light bounces off an object, while refraction is when light bends while passing through an object.
E.g. When you look at a mirror the light bounces of the mirror from different angles, so you can see your reflection. If you point light or a laser pointer at a mirror, it will reflect to the wall in front of the mirror.
Refraction is when light bends.
E.g. When there is a rainbow in the sky, the light from the sun is being refracted from the particles of water and splits the light up into different colors.
- When a ray of light goes from rare medium to denser medium, then as we increase the angle of incident, angle of refraction also increases, the angle of incidence for which angle of refraction become 90 is called critical angle.
- The complete reflection of light ray reaching an interface with less dense medium when angle of incidence exceeds the critical angle is called total internal reflection.
Phenomena based on Total internal reflection
- Mirage formation in desert.
- The air bubble in glass paper weight appear silver due to TIR.
- Sparkling of diamond.
- Optical fibres are based on TIR.
SCATTERING OF LIGHT
- When the size of the particle of medium is of order wavelength of light, the beam of light, is redirected/ deviated in different direction, this is called scattering of light.
- Red color is scattered least (this is why danger light are of red color) and violet color is scattered most.
- Sky appear blue due to scattering of light. Red during sunset and sunrise is also due to scattering of light.
- Clouds appear white.
- In outer space the sky appears black and sun appears white as there is no atmosphere thus no particles to scatter light.
- When a ray of light passes from one medium to other, it bends or deviate from its path, this phenomenon of bending of light is called 'refraction of light.'
- On travelling from one medium to other the wavelength and velocity of light changes but frequency remains same.
Law of Refraction
The incident ray, the refracted ray and normal at the point of incidence all lie in the same plane.
The ration of sine of angle of incidence to the sine of the angle of refraction for a given medium is a constant. The constant is equal to refractive index of second medium w.r.t. first medium.
Refraction Phenomena
- Twinkling of stars.
- River seem shallow, coin in beaker filled with water, pencil in beaker appear broken.
- At sunset and sunrise Sun appear above horizon.
- The duration of day appear to be increases by near 4 minutes due to atmosphere refraction.
- Writing on a paper appear lifted when a glass slab is placed over the paper.
Difference between Refraction and Reflection.
Reflection is when light bounces off an object, while refraction is when light bends while passing through an object.
E.g. When you look at a mirror the light bounces of the mirror from different angles, so you can see your reflection. If you point light or a laser pointer at a mirror, it will reflect to the wall in front of the mirror.
Refraction is when light bends.
E.g. When there is a rainbow in the sky, the light from the sun is being refracted from the particles of water and splits the light up into different colors.