8. REFRACTION
The change in direction of path of the light when it
passes from one transparent medium to another
transparent medium , is called refraction. The
refraction of light is essentially a surface
phenomenon
10. RDT
RARER DENSER TOWARDS THE NORMAL
DRA
DENSER RARER AWAY FROM THE NORMAL
Air to Water
Water to air
11. The ray of light incident normally on
the surface passes undeviated
12. LAWS OF
REFRACTION
The incident ray , the refracted ray and the
normal to the point of incidence ,all lie in the
same plane.
The ratio of sine of the angle of incidence i to
the sine of angle of refraction r is constant for
the pair of given media
sin i/sin r = constant
13. The constant is called the refractive
index of the second medium wrt to the
first medium.
1 2
17. Condition for a ray of light
to pass undeviated
Incident Normally
RI of both the medium is
same , i.e Same mediums
18. Factors affecting the
Refractive Index of the
medium
Nature of the medium
Temprature - T Rise , Speed Rise , RI Fall
Red light - Maximum Speed , Minimum RI
Violet Light - minimum Speed , max RI
19.
20. 1 2
1 2
= 1
2 1
Principle of
Reversibility of
Light
2 1
* = 1
27. Factors affecting the
angle of deviation
Angle of Incidence
1.
During Minimum Deviation
Angle of incidence = angle of emergence
Refracted ray inside the prism is parrallel to the
base of the prism.
28. Refractive Index is directly proportional
to the Deviation
Deviation is directly proportional to the
Angle of Prism
Violet is deviated the most and red is
deviated the least.
Flint Glass Prism > Crown Glass Prism
31. SHIFT DEPENDS ON
Directly proportional to RI
Thicker the medium more is the
shift
Shift is more for Violet Light and
Less for Red Light.
32. Critical Angle
Critical Angle is the angle of
incidence in the denser medium
corresponding to which the angle of
refraction in the rarer medium is 90
degree.
33. CASES TO LEARN
When the angle of incidence is
small than critical angle
When the angle of incidence is
equal to critical angle.
When the Angle of Incidence is
Greater than the critical Angle.
Incident is partly reflected
and partly refracted
Angle of Refraction
becomes 90 degree.
Total Internal Reflection is
Obtained.
34. Factors Affecting the
Critical Angle.
Critical Angle is directly
proportional to the wavelength
of the light.
Critical Angle increases with
increase in temperature.
35. Essential
Condition for TIR
The light must travel from a
denser medium to a rarer
medium
Angle of Incidence must
have to be greater than
critical angle.
36. SOME
CONSEQUENCES
On a hot sunny day , a driver
may see a pool of water (or
wet road) in front of him at
some distance. Known as
Mirage often obtained in
desert.
A crack in glass vessel often
shines like a mirror/
A peice of diamond sparkles
when viewed from certain
directions.
