Transcript
Why is the sun look bigger if it is rising?Why is fish look bigger in the bottle? Why is some thing look bigger under the magnifying?
Allah berfirman di dalam Al Qur’an : 24 ayat 39
Yang artinya :
Dan orang-orang yang kafir amalan-amalan mereka laksana fatamorgana di tanah yang datar yang disangka air oleh
orang yang dahaga, tapi bila didatanginya air itu dia tidak mendapatinya sesuatu
apapun.
Refraction Is The change direction or bending of
l ight at the inter face between two transparent media.
It occur when the speed of l ight changes
Look at the picture below !
Incident ray normal l ine
refracted ray• i = incident angle is the angle between the
incidence ray and normal to the surface at the incidence
• r = refracted angle is the angle between the refracted and the same normal
i
r
Note
The rays enter more optically dense medium where they travel more slowly, the refracted rays bend toward the normal.The angle of refraction is smaller than the angle of incidence
The rays passes from more optically dense medium where they travel more quickly, the refracted rays bend away from the normal.The angle of refraction is bigger than the angle of incidence
Refraction is caused by :The ray change speed.
The ratio of speed c of light in vacuum to the speed v of light in medium is defined index of refraction (n)
C. vacuum------------V. Medium
n =
Table INDEX OF REFRACTION
Substance index of refractionGases
Air 1.000293Carbon dioxide 1.00045
LiquidsWater 1.333Ethyl alcohol 1.361
SolidsIce 1.309glass 1.6 – 1.9Diamond 2.419
Resume
1. If rays enter to more optically dense medium the refracted rays bend toward the normal
2. If rays exit from more optically dense medium the refracted rays bend backward the normal
Look at the figure !
Total internal reflection
This phenomena can use to explain (light propagating) fatamorgana
(light propagating) fatamorgana become light exit from dense medium
(light propagating) fatamorgana become if incidence angle more than critical angle
Critical angle is incidence angle that have refracted angle of 90o
Inter face
Dense Medium
Ik
Total internal reflection of light
Ik = critical angle is incidence angle that have refracted angle of 90o
Source light
LENSES
Convex lenses (Magnifying Lenses)A glass which makes thing look bigger is use full in many ways. Watch makers, scientists and people who cannot see nearIt is thicker in the middle than at the edges. It can used to collect the rays of the sun on the spot, and in this way burn a hole in piece of paper.The spot where the sun’s ray collect is known focal point.The distance between the focal point and the lenses is called focal length.Lenses of different thickness have different focal length
LENSES
Concave lensesIt is thinner in the middle than at the edges. Parallel light rays which are passing trough a concave lens bend towards each other (diverging.In another word it is known diverging lens.
Part of Convex lens
Sumbu utamax x x xM1 F1 O F2 M2
R1
R2
F1 dan F2 = Focal pointM1 dan M2 = Center of curveO = center opticR1 dan R2 = Radius of curve
Dra wing p ic ture
x x x xM1 F1 O F2 M2
SiSo
So = space of object (jarak benda)Si = space of image (jarak bayangan)
Untuk m e m p e rm uda h da la m m e lukis ba ya ng a n, le ns a c e kung da p a t d ig a m ba rka n s e p e rti ini
X x x x xM1 F1 O
-
Me lukis ba ya ng a n p a da le ns a c e kung
X x x x xM1 F1 O
-
Sifat bayangan :1. Tegak2. Diperkecil3. maya
Me lukis ba ya ng a n p a da le ns a c e kung
X x x x xM1 F1 O
-
Sifat bayangan :1. Tegak2. Diperkecil3. maya
Relation ship between so, si and f
1/So + 1/Si = 1/f
So = jarak bendaSi = jarak bayanganf = jarak fokus
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