Post on 08-Apr-2018
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8/6/2019 53B LIGHT Refraction Total Internal Reflection
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Total Internal Reflection and Critical Angle
Vedio
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Normal
Ray box
Semi-circular block glassi
r
i = 42o
r = 90o
i = Critical angle, c = 42o
Refractive index, n = sin Vsin m
n = sin 90 = 1sin c sin c
n = 1/(sin 42o) =
Tangent
when r = 90o
What happen if i is biggerthan c?
The light is reflected internalat the surface in a medium(glass).
Its known as Total Internal
Reflection
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Normal
Ray boxTangent
State two conditions for total internal reflection could occur.
ci
Glass: high
density
Air: low
density
i) Light ray passes from a denser medium to a less dense medium
ii) The angle of incidence (in the denser medium) is greater than the
critical angle.
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The shape of glasses:
Glass Block
Semi-circularGlass Prism Block
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Prism: Observe the changes of the ray when the angle of incidence ray
in prism is increased.
Vedio
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Figure a Figure a
PQ
PQ
2. Determine the critical angle of prism which are used.
1. How do you explain the condition of the light which passes in theprism?
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Natural Phenomenon Involving Total Internal Reflection
1. Mirage (Logamaya / fatamorgana)
Object(cloud)
Warm air layer
(low density)
Cool air layer
(high density)
Image(cloud)
The ray from objectis bent (refracted)
Observer
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Lagu: Logamaya (Amok)
Logamaya yang temberang
Salah paham menyesatkanSinar cahya dari awan
Dibiaskan dan dipantulkan
Dari lapisan udara kesejukan
Ke lapisan udara kepanasanCahaya dibias dan dipantul dalam (penuh)
Medium yang sama
Ke mata perhati
Yang kelihatan imej awan-awan
Bagai kolam ikan di tengah jalanan
Aku manusia
Yea, yeah.
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2. Rainbow
Discuss;
How does it occur
The phenomenon of light that is involved
Why it is being colourful?
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3. Diamond
Discuss;
i) Refractive index (low or high)
ii) Phenomenon of light
iii) The effect when being exposed to light
Lihat intan dari arang dari lumpur terpendam, lama himpitan kepanasan kini barangbernilai.
Mampukah dirimu jadi seperti itu, atau dirimu hancur lebur.
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The Application of Total Internal Reflection
1. Periscope
Object
Image
Prism
Prism
Observer
Discuss;
The use of the device
The main components and its
functions
The arrangement of prisms
How does it work
The phenomenon of light
Characteristics of image
The advantage of prisms
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2. Binocular
Discuss;
The use of the device
The main components and its
functions
The arrangement of prisms
How does it work
The phenomenon of light
Characteristics of image
The advantage of prisms
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3. Bicycle and Car Reflector and Cat Eyes
Discuss;
The shape of prism
How does it work
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4. Optical Fibre
Discuss;
The use of the device
The main components
How does it work
The phenomenon of light