understanding refraction of light
TRANSCRIPT
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Lets Do Some Activity
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WATER & STRAW
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5.2 Understanding
Refraction of Light
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Refraction
Is due to a change in the speed of
light as it passes from one medium
to another.
Referred to as bending of light.
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Bending of light
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Reflection?
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Reflection
The angle ofincidence
=
The angle ofreflection
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New Verb
Incident Ray
The ray in the first medium
Angle of Incident, I
The angle between the incidentray and the normal.
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New Verb
Refracted Ray
The light ray in the second medium
Angle of Refracted
The angle between the refracted ray andthe normal.
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How the light ray
moved in the twodifferent medium?
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Incident RayNormal
Refracted Ray
i
r
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Bending of light can happen in two
different situation :
Less dense medium to
densermedium
Densermedium to less
dense medium
Figure A Figure B
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FST = Fast to Slow, Towards Normal
If a ray of light passes across the boundaryfrom a material in which it travels fast into a
material in which travels slower, then the light
ray will bend towards the normal line
SFA = Slow to Fast, Away From
Normal
If a ray of light passes across the boundary
from a material in which it travels slow into a
material in which travels faster, then the light
ray will bend away from the normal line.
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Refractive Index
Refractive index, n
The speed of light will decreased whenit enters an optically densermedium.
Increase when it enters an optically less
dense medium.
iumhtInTheMedSpeedOfLigairhtInVacumSpeedOfLign /
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Refractive Index Table
MEDIUM REFRACTIVE INDEX,n
Vacuum 1.00
Air 1.0003 = 1.00Water 1.33
Ethanol 1.36
Glycerin 1.47Crown Glass 1.52
Diamond 2.42
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Laws of Refraction( SNELLS LAW)
i. The incident ray, the refracted ray and
the normal all lie in the same plane.
ii. The ratio of the sine of the angle of
incidence ( sin i ) to the of the angle of
refraction ( sin r) is a constant
mediumr
vacuumin
sin
sin
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Real Depth & ApparentDepth
Real depth : The distance between the
water surface and the object. (D)
Apparent depth: The distance between
the water surface and the image. (D)
',
,Re
DpthApparentDe
DalDepthn
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DD
image
object
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LUCKY CHARMEDNUMBER ZERO
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F lash Mov ie
http://localhost/var/www/apps/conversion/tmp/scratch_8/refraction.swf -
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QUESTION1
If the speed of light in vacuum is3x 108m s-1 and the refractive
index of glass is 1.5.
Calculate the speed of light inglass.
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ANSWER
iumhtInTheMedSpeedOfLig
airhtInVacumSpeedOfLign
/
v
ms18
1035.1
18100.2
msV
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QUESTION2
A light ray travels from the medium air tomedium glass. If the angle of incident is andthe refractive index of glass is 1.5.Calculate the angle of refraction.
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ANSWER
n
isinsin
5.1
30sinsin
r
33.0sin r
47.19r
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QUESTION3Refractive index of ice is 1.31 and
the speed of light in vacuum is 3 x
108 m s-1.
Calculate the speed of light in ice.
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ANSWER
iumhtInTheMedSpeedOfLig
airhtInVacumSpeedOfLign
/
v
ms 1810331.1
181029.2
msV
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QUESTION4
A light ray travels from the ice medium to the airmedium. If the speed of light in vacuum is 3 x108 m s-1 and the refractive index of glass is1.31. Calculate the angle of refraction,
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ANSWER
rn
sin
sin
15sin)31.1(sin
339.0sin
8.19
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QUESTION5
A light ray travels from the liquid medium tothe air medium. If the angle of incident is 45degree and the angle of refraction is 60degree. Calculate the refractive index.
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ANSWER
mediumr
vacuumin
sin
sin
45sin
60sinn
22.1n
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QUESTION6
A light ray travels from the glass medium tothe air medium. If the angle of incident is 25degree and the refractive index of glass is1.5. Calculate the angle of refraction.
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ANSWER
r
in
sin
sin
25sin5.1sin i
34.39i
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Cut & Paste Puzzle
Have you understand about the less
dense medium and denser medium?
Now, show how the light rays travel:-
Less dense medium to denser medium.
Denser medium to less dense medium.