2. OBJECTIVIES OF LEARNING
Student can to explain the properties of light
Student can to explain the law of light
reflection, draw image formation on the flat
mirror, concave mirror, and convex mirror
Student can to explain the law of light
refraction, draw image formation in concave
lens, and convex lens and explain the image
properties in concave lens and convex
lens, calculate the power of lens
3.
4. Light is an elektromagnetic wave, namely the
wave the vibration of which is electric field and
magnetic field. Different with sound, light can spread
without medium, so light can spread in vacuum.
That’s why, sunlight can arrive to the earth
eventhough between the sun and the earth is found
vacuum space
5. While several properties of light among other are:
• Spreading according to straigt Line
• Has energy
• Can be seen
• Radiated in the from of radiation
• Has spreading direction perpendicular to vibration
direction
• Can experience reflection, refraction, inter
ference, diffraction, and polaritation
6. LIGHT REFLECTION
Law of Light Reflection:
Incident angle a. Incide angle, normal line and reflected ray
mirror
lie on one flat plane
i = sudut datang
b. Incident angle is equal to reflected angle (i
r = sudut pantul
Normal line = r)
Reflected ray lie
The Kinds of Light Reflection
Specular Reflection Diffuse Reflection
7. Light Reflection on flat Mirror
a. Virtual image
b. Upright as the body
c. Same size with the body
d. Facing perverted with the body
e. Distance of the body to the mirror is
equal to distance of image to the
mirror
8. Light Reflection in Concave Mirror
1. Incident ray which is paralles to main
axis ef the mirror will be reflected
passing through the focal point F.
2. The incident ray passing
through the focal point F will be
reflected parallel to main axis.
3. The incident ray passing through
center point of curvature of mirror
P will be reflected back through
that center point of curvature.
9. Formation of a shadow on the concave mirror
Concave mirror equation
or
10. An object is placed 20 cm infront of a concave mirror
with radius of curvature of 30 cm. What is the
distance of image to the mirror and the image
magnification ?
Solution:
Given: S = 20 cm
R = 30 cm
Asked: S’ and M ?
Answer:
So, the image magnification is 3 time
So, the image distance is 60 cm in front of mirror
11. Light Reflection in Convex Mirror
1. The incident ray parallel to
main axis is reflected
seemed comes from focal
of the mirror (F).
2. Incident ray to focal point
(F) is reflected parallel to
main axis.
3. Incident ray to center of
curvature of mirror P is
reflected back seemed
comes from the center
point of curvature (on the
same line).
13. Light Refraction
Light refraction is phenomenon of bending
of light that spreads from one medium to
another medium which density are different.
Law of refraction:
1. Incident ray, refracted ray, and normal
line lie on one flat plane and those three
intersect at one point.
2. The ratio of projection of incident ray
refracted ray at boundary plane between
those two medium is constant number is
defined as index of refraction.
14. Convex Lense
1. Incident ray parallel to main axis is
refracted through active focus F1.
2. Incident ray through positive focal
point F2 is refracted parallel to main
axis.
3. Incident ray through lens center point
O is continued without experiencing
refraction.
15. Concave Lens
1. Incident ray Parallel to main
axis is refracted seemed
comes from active focal point
F1.
2. Incident ray seemed goes to
passive focal point F2 is
refracted parallel to main axis.
3. Incident that goes to optic
center point of lens is
continued without refraction.
16. An object is put 20 cm infront of a convex lens. If focus distance of the lens
is 15 cm, what is:
a. Image distance from the lens
b. Image magnification
c. Properties of image
Solution:
Given: S = 20 cm
f = 15 cm
Asked: a. S’..?
b. M..?
c. Properties of image..?
17. Answer:
So, image
magnification is 3
times
Properties of image is
real, inversed enlarged.
So, image distance from the
lens is 60 cm behind the
lens
