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SREE NARAYANA TRAINING COLLEGE POOCHAKKALB.Ed 2013-2014

SUBMITTED BY

NAME : DEEPA KRISHNAN OPTION SUBJECT : PHYSICAL SCIENCE REG.NO : 13383010

SUBMITTED TO

MRS.LINIMOL K.S LECTURER (PHYSICAL SCIENCE)

POWERPOINT PRESENTATION ON

LIGHT AND SOME RELATED PHENOMENON

REFRACTION

When a ray of light travels from a medium to another having a change in optical density the direction of the wave slightly changes. This is known as REFRACTION

When the incident ray travels from a less optically dense medium (low n) to a more optically dense medium (high n) then the refracted ray bends towards the normal.

LAWS OF REFRACTION

AirGlass

Normal

Higher speed (lower index of refraction)

Lower speed (higher index of refraction)

θi

θr

Refracted ray bends away from the normal

LAWS OF REFRACTION

AirGlass

Higher speed (lower index of refraction)

Lower speed (higher index of refraction)

Refracted ray bends towards the normal

θi

Normal

θr

The apparent depth is less than the real depth because rays of light are refracted from the normal as they leave the water.

The light rays appear to come from a point I which is a virtual image.

Real depth and Apparent depth

Apparent Depth

Objects under water always appear to be nearer to the surface than they actually are

An optical illusion is formed!

TOTAL INTERNAL REFLECTION

If the angle of incidence of a ray is greater than a certain critical angle the ray will reflect rather than reflect This principal is responsible for the properties of fiber optic cables.

TOTAL INTERNAL RFLECTION

MIRAGE AN EXAMPLE FOR TOTAL INTERNAL REFLECTION

REFLECTION

•Diffuse reflection (rough)

reflects light in many different directions,

•Specular reflection (smooth)

reflects light in only one direction

Smooth – variations in surface

TYPES OF REFLECTION

DISPERSION The separation of light into colors arranged

according to their frequency, by interaction with a prism or diffraction grating.

RAINBOWS White light separates into different colors

(wavelengths) on entering the raindrop because red light is refracted by a lesser angle than blue light. On leaving the raindrop, the red rays have turned through a smaller angle than the blue rays, producing a rainbow.

THANK YOU