REFRACTION

1

REFRACTION
( FOR STANDARD)
BY- DEVENDRA KUMAR GIRIJA SHANKAR
2


WHAT DO YOU OBSERVE IN THE PICTURE GIVEN BELOW ?

3

THE EFFECT OF THE BRUSH
AND THE TOY IS DUE TO REFRACTION.
BROKEN

4
EFFECT OF LIGHT
WHEN LIGHT FALLS ON AN OBJECT IT IS PARTLY
REFLECTED, PARTLY REFRACTED AND PARTLY ABSORBED.
MAXIMUM REFRACTION OCCURS IN TRANSPARENT MEDIUM.

5
REFRACTION IS ...
BENDING OF LIGHT WHEN IT PASSES FROM ONE MEDIUM
TO ANOTHER MEDIUM OF DIFFERENT OPTICAL
DENSITY.
DUE TO CHANGE IN VELOCITY OF LIGHT WHEN IT
PASSES THROUGH MEDIUMS OF DIFFERENT
OPTICAL DENSITIES.
DUE TO CHANGE IN WAVELENGTH OF LIGHT WHEN
IT PASSES THROUGH DIFFERENT MEDIUMS.
NEXT
6

WAVELENGTH OF LIGHT CHANGES WHEN IT PASSES FROM
ONE MEDIUM TO ANOTHER MEDIUM
7
LIGHT RAY MOVES AWAY FROM THE NORMAL WHENIT
TRAVELS FROM DENSER TO RARE MEDIUM.

AIR
r
i
WATER
8
LIGHT RAY MOVES TOWARD THE NORMAL WHEN ITPASSES
FROM RARE TO DENSER MEDIUM.

AIR
i
r
WATER
9
REFRACTIVE INDEX
FOR A GIVEN PAIR OF MEDIUMS WE DEFINE A CONSTANT
FOR REFRACTION KNOWN AS REFRACTIVE INDEX.
IT CAN BE DEFINED IN TERMS OF.

• DEPTH

• VELOCITY

• SNELLS LAW

NEXT
10
REFRACTIVE INDEX IS DEFINED AS RATIO OF REAL
DEPTH TO APPARENT DEPTH OF OBJECT IN THE MEDIUM.

NORMAL
O
AIR
WATER
VIRTUAL OBJECT
P
ACTUAL OBJECT
R
11
VELOCITY OF LIGHT IS DIFFERENT IN DIFFERENT
MEDIUMS.

AIR
GLASS
REPEAT
12
VELOCITY OF LIGHT IS DIFFERENT IN DIFFERENT
MEDIUM.

AIR
GLASS
REPEAT
13

REFRACTIVE INDEX OF A MEDIUM IS DEFINED AS THE
RATIO OF VELOCITY OF LIGHT IN VACCUM TO VELOCITY
OF LIGHT IN THE MEDIUM.

µ c / v
14
SNELLS LAW- n1 sin ?1n2 sin ?2
where n1,n2 are refractive
indices of medium 1and 2 respectively
?1,?2 are angle of incidence and
angle of refraction

15
Observe the phenomenon of refraction when light
ray passes from rarer medium to denser medium.
Click to observe
16

REFRACTIVE INDEX OF WATER WITH RESPECT TO AIR

Sin i
-----------
Sin r

AIR
i
r
WATER
17
Observe the phenomenon of refraction when light
ray passes from denser medium to rare medium.
Click to observe
18
CLICK TO INCREASE ANGLE OF INCIDENCE
19
CLICK TO INCREASE ANGLE OF INCIDENCE
20
CLICK TO INCREASE ANGLE OF INCIDENCE
21
CLICK TO INCREASE ANGLE OF INCIDENCE
22
(No Transcript)
23
The angle of incidence in the denser medium for
which angle of refraction is 90º is known as
CRITICAL ANGLE.


C
24
Refractive index of air with respect to glass

sin i / sin r
sin c / sin 90

Refractive index of glass with respect to air

sin 90/sin c
1 / sin c

µ 1/ sin c
25
What do you expect if angle of incident is
greater than critical angle.?
To check your answer click ..
MATERIAL CRITICAL ANGLE(DEGREE)
DIAMOND 24.5
FLINT GLASS 37
CROWN GLASS 41.1
PLAIN GLASS 41.2
WATER 48.7
ICE 49.8
26
CLICK TO INCREASE ANGLE OF INCIDENCE
27
CLICK TO INCREASE ANGLE OF INCIDENCE
28

CLICK TO INCREASE ANGLE OF INCIDENCE
29
(No Transcript)
30
TOTAL INTERNAL REFLECTION

• WHEN THE ANGLE OF INCIDENCE IN THE DENSER
  MEDIUM IS GREATER THAN THE CRITICAL ANGLE THE
  RAY UNDERGOES TOTAL INTERNAL REFLECTION.
  
  
• THAT IS ,ALL THE INCIDENT LIGHT IS REFLECTED AND
  NO REFRACTION OCCURS.

31

TOTAL INTERNAL REFLECTION HAS MANY PRACTICAL
APPLICATIONS

• SPARKLING OF DIAMOND

• RAINBOW FORMATION

MIRAGE
PERISCOPE AND BINOCULAR(PRISM)

• OPTICAL FIBRE

NEXT
32
Refraction of Light by Diamonds The brilliance of
diamonds is due to their high refractive index,
which is about 2.4. The skill of the gem-cutter
lies in angling the facets of the stone so that
each light ray entering it is reflected many
times before it emerges again. The refractive
index is slightly different for each colour of
light, so the light is split into its coloured
components, giving rise to the multicoloured
fire of diamonds.
33
MIRAGE
MIRAGE IS FORMED WHEN LIGHT PASSES FROM COOLER
AIR TO WARMER AIR AND IS BENT TOWARDS THE
HORIZONTAL LINE OF VISION AND EVENTUALLY IT IS
MADE TO TRAVEL UPWARDS BY TOTAL INTERNAL
REFLECTION PRODUCING A VIRTUAL IMAGE.
34
OPTICAL FIBRE
Fibre-Optic Cable A bundle of optical fibres
passes easily through the eye of this needle.
Fibre-optic cables are rapidly replacing bulky
copper-wire cables in the telecommunications
industry. A single pair of such cables can carry
over a thousand conversations simultaneously.
35
Binoculars
Binoculars Binoculars present a different view
to each eye to enable a user to perceive depth.
Each half of a pair of binoculars is essentially
a telescope however, binoculars often
incorporate prisms so that they are more compact
than a telescope of comparable power.
36
TO KNOW MORE ABOUT REFRACTION VISIT OUR WEBSITE
OPTICA
37
ACKNOWLEDGEMENT
Mr. V. K SODHI .
ENCARTA Freespace.virgin.net/garethjames/virtual/o
ptics/Refraction/refraction.html CLIP ART