Partial Reflection

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Partial Reflection Refraction
A phenomenon in which some of the light that is
traveling from one medium into another is
reflected some is refracted at the boundary
between two media.
air

glass
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The amount of reflection compared with the amount
of refraction depends on the angle of incidence.
large angle of incidence, most of the light is
reflecting
small angle of incidence, most of the light is
refracting
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The Sun is high in the sky, so the angle of
incidence is low. Most of the sunlight is being
refracted.
The Sun is setting, so the angle of incidence is
high. Most of the sunlight is being reflected.

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Angle of refraction increases as angle
of incidence increases.







(e.g. a fish)?
At the critical angle, the refracted ray is at
an angle of 90o.
Total internal reflection is the phenomenon in
which incident light is not refracted but is
entirely reflected back from the boundary. It
happens only when light travels from a medium
in which its speed is lower to a medium in
which its speed is higher.
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Applications of Total Internal Reflection

• optical fibres

cladding (made of another type of glass with a
lower refractive index)?
core (made of glass)?

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Uses of Optical Fibres

• communication

Advantages (as compared to copper wire cables)
1. The signals are not affected by electrical
storms.
2. They lose less energy.
3. They are smaller lighter.
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• endoscopes