reflection,refraction,total internal reflection,fibre optics

                                 REFLECTION

when a ray of light is incident on a mirror it gets reflected in accordance with the following laws

First law

The incident ray, the reflected ray and the normal at the plane of incidence all lie in the same plane

Second law

The angle of incidence is equal to angle of refraction

LATERAL INVERSION

The sideways reversal of the image formed by a plane mirror is known as lateral inversion

 

 REFRACTION

 The phenomenon of bending of light from its straight line path as it passes from one medium to another with  change in density

LAWS OF REFRACTION

FIRST LAW

The incident ray,the refracted ray, and the normal to the surface of separation at the point of incidence all lie in the same plane.

SECOND LAW

The ratio of the sine of angle of incidence and the sine of angle of refraction is constant  for a given pair of media

sin i/sin r =constant ,This constant is called refractive index(RI)

Another equation for RI= Speed of light in vacuum/Speed of light in medium

On what factors does the refractive index of a medium depend?

Nature of medium

nature of surrounding medium

wavelength of light used

temperature

REFRACTION THROUGH GLASS SLAB

TOTAL INTERNAL REFLECTION

It is the Phenomenon in which a ray of light traveling at an angle of incidence greater than the critical angle from a denser to rarer medium is totally reflected back into the denser medium,obeying laws of reflection

The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90'

APPLICATIONS OF TOTAL INTERNAL REFLECTION

1 Sparkling of Diamond

2.Mirage formation

 It is an optical illusion obseved in deserts or over heated surfaces, due to which observer sees a pond of water at some distance. The lower layer of air near earth surface get heated  than the upper layer then at lower layer density of air is less.So refraction take place from rarer to denser medium

LOOMING

This mirage observed in cold region. The lower  layer of air is cooler an denser while upper layer is hotter and rarer. When refraction of light take place the ships appears to hang inverted in the air

3.Optical fiber - Used to transmit light through long distance

4.periscope, binoculars

5.Reflector light of Bicycle

EXPLAIN THE PHENOMENON OBSERVED IN NATURE DUE TO REFRACTION
1. The sun is visible to us about 2 minutes before and actual sunrise

2.A fish at the bottom of the tank appears to be raised its position.

3.AN OBJECT PLACED AT THE BOTTOM OF BEAKER APPEARS TO BE RAISED
4.Twinkling of stars is due to refraction of its light passes through different layers of atmosphere with different densities