chapter 9 physics for junior high school viii optical tools optical tools : tools used to see by...
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CHAPTER 9
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
OPTICAL TOOLS
OPTICAL TOOLS
Optical tools : tools used to see by human Natural : eye Made : tools to help human in observing objects that
can not be seen by naked-eye : camera, projector, magnifying glass, microscope, and telescope.
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Eye has its own parts, cornea, iris, pupil, lens, retina, and optical nerve.
EYE
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
EYE
When our eye is relax (not accommodating), the lens becomes flat so that the focus space is the biggest, and the long space object is focused to retina.
Making the lens thick and flat(eye accommodation) in order to have the different space object can be focused by
The image in retina is real, inverse, and reduced.
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
THE RANGE OF SIGHTPP PR
The range of sight
Eye can see clearly if the object is in the range of sight, between near point (punctum proximum) and far point (punctum remontum).
Normal eyeNear point = 25 cm
Far point = limitable
= 25 cm= ∞
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Defect is possible to occur if both far point and near point move from their proper position at normal eye (emetrop eye).
There are 3 kinds of eye defect caused by the moving of the far and near point, they are far sighted (myope), long-sighted (hypermyope), and old eye (presbyope).
DEFECT OF EYE
Gambar 9.3 Pembentukan bayangan pada mata: (a) Normal, (b) Miopi, (c) Hipermetropi
Sumber : BSE VIII SMP
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Camera works almost like eye, it consists of one closed box that has a small whole in its front window. By the small whole the shaft of light then come in through the positive lens called objective. Objective lens forms the real image, inverse, and reduced at a film plate.
Camera has 3 light meter, namely range finder, shutter, and diaphragm.
CAMERA
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Function of the parts in cameraa. Lens, to form the real
image, reduced, and reverse.
b. Film, as the place for image.c. Aperture (diaphragm gap),
as the way of light to come in. diaphragm, to control the light coming through aperture.
CAMERA
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Magnifying glass is the simplest optical tool, because it only consisting of one convex lens
Magnifying glass function is to observe small objects so that look bigger.
The type of image are virtual, standing, and zoomed.
There are 2 ways in using it, with accomodated eye, and non-accommodated eye.
MAGNIFYING GLASS
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Microscope is a tool to observe super-small objects..
It has 2 convex lens, objective lens, and ocular lens.
Objective lens is a lens that is close to the observed-object.
Ocular lens is a lens that is close to observer’s eye.
MICROSCOPE
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Telescope is an optical tool that is used for observing far objects so that look nearer.
It is discovered for the first time by Galileo Galilei.
There are 2 kinds of telescope, astronomical telescope, and earth telescope.
TELESCOPE
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
Periscope is a telescope that is used in submarine.
Periscope works to see the sea surface without come up the submarine.
Periscope consists of 2 convex lens, objective and ocular lens. And 2 isosceles angle-prism.
PERISCOPE
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
THANK YOU
PHYSICS FOR JUNIOR HIGH SCHOOL VIII
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