Transcript Optics

OPTICS
Optics
• Study of light and its
properties
Light
• Light helps us to see
• Light may be defined as
an electromagnetic
energy
Uses of Light
• Sun light helps in the
preparation of Vitamin D
in our body
• Light helps in
photosynthesis in plants
Travel in light
• Light travel in a straight
line
• Light travel as a wave
• Particle nature of light
Properties of light
• Light gets reflection from the
smooth surface and reflection
gives images
• Light gets refracted when light
goes from one medium to
another medium the part of
light in bend
Types of Optics
• Physical optics
• Physiological optics
• Geometrical optics
Physical optics
• Wave optics
• Quantum optics
Wave optics
In it light is treated as a Wave
* Interference
(i) Constructive
(ii) Destructive
* Diffraction
(i) Fresnel
(ii)Fraunhofer
* Polarization
Wave optics
Interference
• When Two waves of light travel
along the same path the effect
produced depends upon
whether or not the ways are in
phase with one another.
Constructive
• If they are in phase the
resultant wave will be a
summation of the two and this
is called Constructive
interference
Destructive
• If the Two waves of equal
amplitude are out of phase by
half a cycle, they will cancel
each other Destructive
interference.
Diffraction
Diffraction
• When a wave front encounters a
narrow opening or the edge of an
obstruction the wave motion spread
out on the far side of obstruction. It
is as if the edge of the obstruction
acts as a new center from which
secondary wave fronts are produced
which are out of phase with the
secondary wave this phenomenon is
called diffraction.
Polarization
• Light waves are traveling may
or may not be parallel to each
other. If direction are randomly
related to each other the light is
unpolarized / non polarized. If
parallel to each other is called
polarized light.
Quantum optics
• Scattering of light
• Transmission and absorption
• Laser
Geometrical optics
LAWS OF REFLECTION
• The incident ray, reflected ray and the
normal ray to the reflecting surface all
lie in the same plane.
• Angle of incidence(i) = Angle of
reflection(r)
incident ray
normal
reflected
ray
i
r
LAWS OF REFRACTION

Incident ray, refracted ray normal at the point
of incidence are all in the same plane.

The ratio of the sine of the angle of incidence
to the sine of the angle of refraction is a constant
for a given pair of media for a given colour.

The constant is known as refractive index of the
second medium with respect to first medium.
REFRACTION OF LIGHT
• Refraction is defined as the change
in direction of light when it passes
from one transparent medium into
another of different optical density.
Rarer
medium
Denser
medium
Denser
medium
Rarer medium
REFRACTION THROUGH A
TRIANGULAR GLASS PRISM
REFRACTIVE INDEX
• A comparison of the velocity of light in a
vacuum and in another medium gives a
measure of the optical density of that medium.
This measurement is called the absolute
refractive index,(n) of the medium.
Absolute refractive
index =
velocity of light in vacuum
velocity of light in medium
• Refractive index of ;
Air-1
Water-1.33
Cornea-1.37
Crystalline lens-1.38-1.42
Crown glass- 1.52
Flint glass- 1.6
Diamond- 2.5
CRITICAL ANGLE AND
TOTAL INTERNAL REFLECTION
• When the angle of refraction in the
rarer medium is 90 degree, the angle
of incidence in the denser medium is
known as the critical angle of the
denser medium.
• When the angle of incidence in the
denser medium is more than the
critical angle,that ray cannot be
refracted obeying the law of
reflection
• Diagram
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