refraction of light
DESCRIPTION
Refraction of lightTRANSCRIPT
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WELCOME
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KERALA UNIVERSITY COLLEGE OF TEACHER EDUCATION,KOLLAM
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Refraction of Light
LIGHT
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LIGHT
•What is Refraction?
•What is Optical Density?
•The Laws of Refraction
•The Refractive index
•Angle of Incidence / Refraction
•Total Internal Reflection
•What is Refraction?
•What is Optical Density?
•The Laws of Refraction
•The Refractive index
•Angle of Incidence / Refraction
•Total Internal Reflection
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LIGHT
Refraction is the change in direction of light when it passes from one medium to another.
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LIGHT
If light ray enters another medium perpendicular to boundary, the ray does not bend.
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LIGHT
When the light ray travels from air to water, the refracted ray bends towards the normal.
i
r
air
water
Incident ray
Refracted ray
normal
i – angle of incidencer– angle of refraction
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LIGHT
When the light ray travels from water to air, the refracted ray bends away from the normal.
i
rair
water
Incident ray
Refracted ray
normal
i – angle of incidencer– angle of refraction
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LIGHT
During refraction, light bends first on passing
from air to glass and again on passing from
the glass to the air.
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LIGHT
During refraction, light bends first on passing
from air to glass and again on passing from
the glass to the air.
i
r
Incident ray
Emergent ray
Refracted ray
Reflected rayair
air
glass
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LIGHT
Light slows down when it enters an optically denser medium. The refracted ray bends towards the normal when the second medium is optically more dense than the first.
i
r
air
water
Incident ray
Refracted ray
normal
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LIGHT
Light speeds up when it enters an optically less dense medium. The refracted ray bends away from the normal when the second medium is optically less dense than the first.
air
water i
r
Incident ray
Refracted ray
normal
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LIGHT
Among the 3 transparent mediums (air, water and glass), glass has the highest optical density.
air
water
i1
r1
Incident ray
Refracted ray
glass
i2
r2
Refracted ray
air
water
i1
r1
Incident ray
glass
i2
r2
Refracted ray
Refracted ray
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LIGHT
Take a look at this...
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LIGHT
The critical angle is the angle of incidence in the optically denser medium for which the angle of refraction is 90o.
When i = critical angle,c r = 90o.
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LIGHT
This is called TOTAL INTERNAL REFLECTION.
When i > critical angle, the ray gets reflected internally.
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LIGHT
For TOTAL INTERNAL REFLECTION to take place:
The light ray must travel from an optically denser medium towards a less dense one.
The angle of incidence must be greater than the critical angle.
Direction of light path
i
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LIGHT
How do we calculate the critical angle?
We know that r = 90o…
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Total Internal Reflection in Prisms
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LIGHT
Total Internal Reflection in Prisms
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LIGHT
Fibre Optics
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