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
Light is an elektromagnetic wave, namely thewave the vibration of which is electric field andmagnetic field. Different with sound, light can spreadwithout medium, so light can spread in vacuum.That’s why, sunlight can arrive to the eartheventhough between the sun and the earth is foundvacuum space
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
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 lieThe Kinds of Light Reflection Specular Reflection Diffuse Reflection
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
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.
Formation of a shadow on the concave mirrorConcave mirror equation or
An object is placed 20 cm infront of a concave mirrorwith radius of curvature of 30 cm. What is thedistance of image to the mirror and the imagemagnification ?Solution:Given: S = 20 cm R = 30 cmAsked: S’ and M ?Answer: So, the image magnification is 3 timeSo, the image distance is 60 cm in front of mirror
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).
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.
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.
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.
An object is put 20 cm infront of a convex lens. If focus distance of the lensis 15 cm, what is:a. Image distance from the lensb. Image magnificationc. Properties of imageSolution:Given: S = 20 cm f = 15 cmAsked: a. S’..? b. M..? c. Properties of image..?
Answer: So, image magnification is 3 times Properties of image is real, inversed enlarged.So, image distance from thelens is 60 cm behind thelens