Ray optics

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Physics
Subject :Ray optics: Optical
Instruments
PHYSICS
Physics : Ray Optics

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I'd like to express my greatest gratitude to the people who have
helped & supported me throughout my project. I will treasure the knowledge
imparted to me by Mr. M.Bagdi, my grateful thanks to him for the able
teaching and guidance, his continuous support for the project, from initial
advice & encouragement to this day. I thank Mr. Chotelal, the Lab assistant for
his cooperation.
Special thanks of mine goes to my colleague who helped me in completing the
project by giving interesting ideas, thoughts & made this project easy and
accurate.
I wish to thanks OUR SCHOOL PRINCIPAL MRS. KIRAN AWASTHI for
her_constant_support. .
I wish to thanks my parents for their undivided support & interest
who inspired me & encouraged me to go my own way, without which I would be
unable to complete my project.
Acknowledgement

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KendriyaVidyalayaMhow
I certify that Mas.Akshay Kumarof class XII ‘A’worked on the
project “Ray Optics:OpticalInstuments” under my super vision. He
has completed his work successfully during the session 2012-13.
This project is considered as fulfillments of the AISSCE
Examination conducted by CBSE, New Delhi.
Certificate

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Certificate
(Page No. Certification)
This is certify that this Physics
Investigatory Project work is the soul
propertyof Akshay Kumar
Guptacontaining32pages……….

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Content
1. Acknowledgement
2. Certificate
3. Declaration
4. Introduction to Ray Optics
5. Content
6. Ray Optics
a. the human eye
i) Introduction to human eye
ii) Working of the eye
iii) Defects of vision
b. The Camera
c. The Microscope
i) Simple microscope
ii) Compound microscope
d. The Telescope
i) Refracting type telescope
ii) Reflecting type telescope
e. Early telescopes
f. Telescopes of the world
g. Hubble Space Telescope

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h. Chandra X-Ray Telescope
i. Breaking News (Latest information)
7.Biplography

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Introduction to Ray optics
Optics, branch of physical science dealing with the
propagation and behavior of light. In a general sense, light is
that part of the electromagnetic spectrum that extends from X
rays to microwaves and includes the radiant energy that
produces the sensation of vision (ElectromagneticRadiation ,
Energy; Spectrum, X Ray). The study of optics is divided
into geometrical optics and physical optics, and out of these
branches Geometrical Optics or Ray Opticsare discussed
below.

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The Ray Optics ,uses the geometry of straight lines to account
for macroscopic phenomenon like rectilinear propagation
,reflection ,refraction ,etc. That is why Ray Optics is called
Geometrical Optics.

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Optical Instruments
Optical instruments are the devices which help human eye
i) in observing highly magnified images of tiny
objects ,for detailed examination,eg.Microscope,
ii) ii) in observing very far off objects-terrestial or
astronomical, eg. Telescope.
The essential optical component in making these
instruments are convex and concave, lens and mirrors.
The images are formed by refraction through lenses and by
reflection through mirrors.

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TheHuman Eye

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Fig. Close up photograph of cornea of the human-eye
The entire eye, often called the eyeball, is a spherical
structure approximately 2.5 cm (about 1 in) in diameter with a
pronounced bulge on its forward surface. The outer part of the eye
is composed of three layers of tissue. The outside layer is the
sclera, a protective coating. It covers about five-sixths of the
surface of the eye. At the front of the eyeball, it is continuous
with the bulging, transparent cornea. The middle layer of the
coating of the eye is the choroid, a vascular layer lining the
posterior three-fifths of the eyeball. The choroid is continuous with
the ciliary body and with the iris, which lies at the front of the
eye. The innermost layer is the light-sensitive retina.

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• Working of the Eye

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Light entering the eye passes through a transparent structure called the cornea,
behind which are a clear liquid (the aqueous humor), a variable aperture (the pupil,
which is an opening in the iris), and the crystalline lens. Most of the refraction
occurs at the outer surface of the eye, where the cornea is covered with a film of
tears. Relatively little refraction occurs in the crystalline lens because the aqueous
humor in contact with the lens has an average index of refraction close to that of
the lens. The iris, which is the colored portion of the eye, is a muscular diaphragm
that controls pupil size. The iris regulates the amount of light entering the eye by
dilating the pupil in low-light conditions and contracting the pupil in high-light
conditions.The f-number range of the eye is from about f/2.8 to f/16.
The cornea–lens system focuses light onto the back surface of the eye, the retina,
which consists of millions of sensitive receptors called rods and cones. When
stimulated by light, these receptors send impulses via the optic nerve to the
brain,where an image is perceived. By this process, a distinct image of an object is
observed when the image falls on the retina.
• Defects Of Vision
Inspite of all precautions and proactive action,our eyes may
develop some defects due to various reasons. Three of the
common optical defects of eye are
 Myopia or short sightedness or near sightedness,
 Hypermetropiaor long sightedness or farsightedness
 Presbyopia or old sightedness

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Myopia, also called, common name nearsightedness for
impaired vision in which a person sees near objects clearly while
distant objects appear blurred.
In normal vision, light rays from an object enter the eye and
are focused by the lens (transparent tissue that changes shape
to focus incoming light) onto the retina (the membrane at the
back of the eye that transmits images of external objects to the
optic nerve). In people with nearsightedness, the distance
between the lens and the retina is too long. As a result, light
rays from distant objects focus before they strike the retina.
Near objects appear clearly because light rays from them focus
correctly on the retina.
Nearsightedness is corrected with a diverging lens.

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Possible causes are :
i) Increase in the size of eye ball i.e. distance of the retina
from eye lens increases.
ii) Decrease in the focal length of the eye lens, when the eye is
fully relaxed.

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Hypermetropia, also called, common name farsightedness for a
defect in vision in which a person sees near objects with blurred
vision, while distant objects appear in sharp focus.
In normal vision, light rays from an object entering the eye are
focused by the lens (transparent tissue that changes shape to help
focus incoming light) on the retina (the membrane at the back of
the eye that transmits images of external objects to the optic
nerve). In people with farsightedness, the distance between the lens
and the retina is too short. As a result, light rays from near
objects strike the retina before they are in focus, which causes
blurred vision. Distant objects appear clearly because light rays
from them focus correctly on the retina.
Farsightedness is corrected with a converging lens.

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Possible causes are :
i) Contraction in the size of eye ball i.e. distance of the retina
from eye lens decreases.
ii) Increase in the focal length of the eye lens, when the eye is
fully relaxed.

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Presbyopia, also called old sightedness:With increasing age ,the
cilliary muscles holding the eye the eye lens weaken and eye
loses some of its elasticity. Therefore power accommodation of eye
decreases with age.This defect is called Presbyopia.
Bifocal lenses are used in such cases.

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TheCamera

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Basic Camera Function(Photographic camera)
In its simplest form, the camera is a light-tight container carrying
a lens, a shutter, a diaphragm, a device for holding (and changing)
the film in the correct image plane, and a viewfinder to allow the
camera to be aimed at the desired scene.
The lens projects an inverted image of the scene in front of the camera
onto the film in the image plane. The image is sharp only if the film

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is located at a specific distance behind the lens. This distance depends
on the focal length of the lens and the distance of the object in front of
the lens. To photograph near and far subjects, all but the simplest
cameras have a focusing adjustment that alters the distance between
the lens and the film plane to make objects at the selected distance
produce a sharp image on the film. In some cameras focusing
adjustment is achieved by moving only the front element or internal
elements of the lens, in effect modifying the focal length.
The shutter consists of a set of metallic leaves mounted in or behind
the lens or a system of blinds positioned in front of the film. It can be
made to open for a predetermined time to expose the film to the image
formed by the lens. The time of this exposure is one of the two factors
controlling the amount of light reaching the film. The other factor is
the lens diaphragm, or aperture, an opening with an adjustable
diameter. The combination of the diaphragm opening and exposure
time is the photographic exposure. To obtain a film image that
faithfully records all the tone gradation of the object, this exposure
must be matched to the brightness (luminance) of the subject and to
the sensitivity or speed of the film. Light meters built into most
modern cameras measure the subject luminance and set the shutter or
the lens diaphragm to yield a correctly exposed image.
• The Microscope

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Simple microscope or magnifying glassA
simple microscope is used for observing magnified images of tiny
objects. It consists of a converging lens of small focal length. A
virtual erect and magnified image of the object is formed at the
least distance of distinct vision from the eye held close to the lens.
That is why simple microscope is also called a magnifying glass.
A Magnifying glass magnifying an object

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Compound microscope
Acompound microscope is an optical instrument used for
observing highly magnified images of tiny objects.
Construction:
Two convex lenses form a compound microscope. The object lens is
positioned close to the object to be viewed. It forms an upside-down
and magnified image called a real image because the light rays
actually pass through the place where the image lies. The ocular
lens, or eyepiece lens, acts as a magnifying glass for this real
image. The ocular lens makes the light rays spread more, so that
they appear to come from a large inverted image beyond the object
lens. Because light rays do not actually pass through this
location, the image is called a virtual image.

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A compound microscope
TheTelescope
Telescope is an instrumentused to see distant objects which
cannot be seen by naked eyes.Two types:
 Refracting type telescope:Telescope in which the objective is convex lens
which use phenomenon of refraction.Eg. Astronomical telescope,
terrestrial telescope, galileo telescope, etc.

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Refraction type telescope

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Galileo Galileiborn Feb. 15, 1564, Pisa [Italy] -died Jan. 8, 1642
Galileo's career took a dramatic turn. In the spring of 1609 he heard that in the Netherlands an
instrument had been invented that showed distant things as though they were nearby. By trial and
error, he quickly figured out the secret of the invention and made his own three-powered spyglass from
lenses for sale in spectacle makers' shops. Others had done the same; what set Galileo apart was that he
quickly figured out how to improve the instrument, taught himself the art of lens grinding, and
produced increasingly powerful telescopes. In August of that year he presented an eight-powered
instrument to the Venetian Senate (Padua was in the Venetian Republic). He was rewarded with life
tenure and a doubling of his salary. Galileo was now one of the highest-paid professors at the university.
In the fall of 1609 Galileo began observing the heavens with instruments that magnified up to 20 times.
In December he drew the Moon's phases as seen through the telescope, showing that the Moon's
surface is not smooth, as had been thought, but is rough and uneven. In January 1610 he discovered
four moons revolving around Jupiter. He also found that the telescope showed many more stars than
are visible with the naked eye. These discoveries were earthshaking, and Galileo quickly produced a
little book, SidereusNuncius (The Sidereal Messenger), in which he described them. He dedicated the
book to Cosimo II de Medici (1590–1621), the grand duke of his native Tuscany, whom he had tutored in
mathematics for several summers, and he named the moons of Jupiter after the Medici family: the
SideraMedicea, or “Medicean Stars.” Galileo was rewarded with an appointment as mathematician and
philosopher of the grand duke of Tuscany, and in the fall of 1610 he returned in triumph to his native

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land.

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 Reflecting typetelescope: Telescope in which the objective is
concave mirror which use phenomenon of reflection.
Eg. Newtonian telescope, cassegrain telescope, etc.
NewtonianReflectingtelescope

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Early Telescopes
Although a Dutch optician probably designed the first telescope, it
was Galileo who turned it rigorously on the heavens in the early 17th
century. Galileo used a refracting telescope (top) with a convex lens at
the front and a concave lens at the viewing end. The 18th-century

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refracting telescope (middle) produced images that were blurred
because of the different indexes of its combined lenses. The bottom
scope is a reflecting telescope, which used two mirrors and an eyepiece
lens, a setup that eliminates the problems of long viewing tubes and
color distortion.
Telescopes of the World
Large telescopes are found all over the world. Most large telescopes are
based on high mountaintops, where Earth's atmosphere is thinner and

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does not interfere as much with light from distant star

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Hubble Space Telescope(HST): onboard Discovery space shuttle
The most sophisticated optical observatory ever placed into orbit around Earth.
Earth's atmosphere obscures ground-based astronomers' view of celestial objects by
absorbing or distorting light rays from them. A telescope stationed in outer space
is entirely above the atmosphere, however, and receives images of much greater
brightness, clarity, and detail than do ground-based telescopes with comparable
optics.
The HST is a large reflecting telescope whose mirror optics gather light from

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celestial objects and direct it into two cameras and two spectrographs. The HST has
a 2.4-metre (94-inch) primary mirror, a smaller secondary mirror, and various
recording instruments that can detect visible, ultraviolet, and infrared light. The
most important of these instruments, the wide-field planetary camera, can take
either wide-field or high-resolution images of the planets and of galactic and
extragalactic objects.

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Chandra X-Ray Observatory

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U.S. satellite, one of the National Aeronautics and Space Administration
(NASA) fleet of “Great Observatories” satellites, which is designed to make
high-resolution images of celestial X-ray sources. In operation since 1999 .
It is named in honour of Subrahmanyan Chandrasekhar, a
pioneer of the field of stellar evolution.
Breaking News6Oct, 2012
Melbourne : World’s powerful telescope made in Australia to fast the discovery of
planets and rest of the huge galaxy that cost 400 million dollars($) and has a storing data
capacity at the rate of 40GB per second.It is held inMerksenin west Australia inaugurated
on Friday.

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Multiple Mirror Telescope

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The Multiple Mirror Telescope (MMT) located on Mount Hopkins near Tucson, Ariz., combines the light
collected by its six computer-controlled mirrors into a single image.

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Green Bank Telescope
The National Radio Astronomy Observatory's Green Bank Telescope, Green Bank, W.Va

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