1. The document discusses the working principles of cameras, the human eye, and spectroscopy. It describes how cameras and the eye form images using lenses and how factors like aperture, focal length, and shutter speed affect the image.
2. Spectrometers are described as optical instruments used to study light from different sources and analyze spectra. They have a collimator, telescope, and turntable to direct and analyze light.
3. Spectroscopy is defined as the study of electromagnetic spectra produced by various substances, including analyzing emission, absorption, and electron ejection spectra of atoms.
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POWERPOINT NOT MINE. CREDITS TO THE RIGHTFUL OWNER. I JUST SHARED IT HERE SO I CAN PUT A LINK TO MY BLOG. I'M TOO LAZY TO TYPE ALL THESE ONE BY ONE LOL
Eye defects and lenses
The eye is considered normal, or emmetropic, if parallel light rays from distant objects are in sharp focus on the retina when the ciliary muscle is completely relaxed
The normal eye contracts its ciliary muscle to provide for accomodation.
When the eye cannot function properly, the light entering the eye is not brought into sharp focus on the retina.
Physics ( human eye and the colourful world).Nikhil Dahiya
ppt on human eye and its structure. shows different parts of the eye . helps the student to learn about the eye more breifly.it is a science ppt which will be helpfull . teachers can also take it in the us for letting the students understand better .
Human Eye and Colorful World. Chapter 11 grade 10thMurari Parashar
Chapter 11 Human Eye and Colorful World. Human eye is the optical instrument used which enables us to see.
We will study various natural optical phenomenon like Rainbow formation, twinkling of star, blue and red color of sky etc.
The human eye: is the most valuable and sensitive sense organ and it is a natural optical instrument. The important parts of the eye: Cornea, Iris, Pupil, Eye Lens, Retina.
Power of Accommodation: The ability of the eye to focus objects lying at different distances is called the power of accommodation of the eye.
Least Distance of Distinct Vision Near point: Near point or least distance of distinct vision is the point nearest to the eye at which an object is visible distinctly
The far point of the eye:
Far point of the eye is the maximum distance up to which the normal eye can see things clearly. It is infinity for a normal eye.
The twinkling of a star is due to atmospheric refraction of starlight.
Scattering of light:
When a beam of light falls on an atom, it causes the electron in the atom to vibrate. The vibrating electrons, in turn, re-emit light in all directions. This process is called scattering.
7 Active Technology Solutions Pvt.Ltd. is an educational 3D digital content provider for
K-12. We also customize the content as per your requirement for companies platform providers colleges etc . 7 Active driving force "The Joy of Happy Learning" -- is what makes difference from other digital content providers. We consider Student needs, Lecturer needs and College needs in designing the 3D & 2D Animated Video Lectures. We are carrying a huge 3D Digital Library ready to use.
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The human eye is one of the most valuable and sensitive sense organs in the human body. It enables us to see the wonderful world and colours around us.
Structure of eye:
The human eye has the following main parts:
Cornea: It is the transparent spherical membrane covering the front of the eye. Light enters the eye through this membrane.
Crystalline lens: The eyes lens is a convex lens made of a transparent, soft and flexible material like a jelly made of proteins.
Iris: It is a dark muscular diaphragm between the cornea and the lens. It controls the size of the pupil. It is the colour of the iris that we call as the colour of the eye.
Pupil: It is a small hole between the iris through which light enters the eye. In dim light, it opens up completely due to expansion of iris muscles, but in bright light it becomes very small due to contraction of iris muscles.
Eye defects and lenses
The eye is considered normal, or emmetropic, if parallel light rays from distant objects are in sharp focus on the retina when the ciliary muscle is completely relaxed
The normal eye contracts its ciliary muscle to provide for accomodation.
When the eye cannot function properly, the light entering the eye is not brought into sharp focus on the retina.
Physics ( human eye and the colourful world).Nikhil Dahiya
ppt on human eye and its structure. shows different parts of the eye . helps the student to learn about the eye more breifly.it is a science ppt which will be helpfull . teachers can also take it in the us for letting the students understand better .
Human Eye and Colorful World. Chapter 11 grade 10thMurari Parashar
Chapter 11 Human Eye and Colorful World. Human eye is the optical instrument used which enables us to see.
We will study various natural optical phenomenon like Rainbow formation, twinkling of star, blue and red color of sky etc.
The human eye: is the most valuable and sensitive sense organ and it is a natural optical instrument. The important parts of the eye: Cornea, Iris, Pupil, Eye Lens, Retina.
Power of Accommodation: The ability of the eye to focus objects lying at different distances is called the power of accommodation of the eye.
Least Distance of Distinct Vision Near point: Near point or least distance of distinct vision is the point nearest to the eye at which an object is visible distinctly
The far point of the eye:
Far point of the eye is the maximum distance up to which the normal eye can see things clearly. It is infinity for a normal eye.
The twinkling of a star is due to atmospheric refraction of starlight.
Scattering of light:
When a beam of light falls on an atom, it causes the electron in the atom to vibrate. The vibrating electrons, in turn, re-emit light in all directions. This process is called scattering.
7 Active Technology Solutions Pvt.Ltd. is an educational 3D digital content provider for
K-12. We also customize the content as per your requirement for companies platform providers colleges etc . 7 Active driving force "The Joy of Happy Learning" -- is what makes difference from other digital content providers. We consider Student needs, Lecturer needs and College needs in designing the 3D & 2D Animated Video Lectures. We are carrying a huge 3D Digital Library ready to use.
For more information:
http://www.7active.in
Contact: 040-64501777 / 65864777
9700061777
The human eye is one of the most valuable and sensitive sense organs in the human body. It enables us to see the wonderful world and colours around us.
Structure of eye:
The human eye has the following main parts:
Cornea: It is the transparent spherical membrane covering the front of the eye. Light enters the eye through this membrane.
Crystalline lens: The eyes lens is a convex lens made of a transparent, soft and flexible material like a jelly made of proteins.
Iris: It is a dark muscular diaphragm between the cornea and the lens. It controls the size of the pupil. It is the colour of the iris that we call as the colour of the eye.
Pupil: It is a small hole between the iris through which light enters the eye. In dim light, it opens up completely due to expansion of iris muscles, but in bright light it becomes very small due to contraction of iris muscles.
the current topic contain information about anatomy of human eye and defect in vision and their corrections the p.p.t. also explain dispersion and scattering of light this p.p.t.is very useful f for secondary classes students
In the realm of biology, the human eye is a marvel of nature's engineering, allowing us to perceive the world around us with clarity and detail. It is not only a sensory organ but also a gateway to understanding the physics of light and color. Class 10 Science introduces students to the intricacies of the human eye and its interaction with light, delving into topics such as refraction, dispersion, and the perception of color. In this detailed study guide, we will explore these concepts comprehensively to aid students in understanding this fascinating aspect of biology and physics.
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This presentation includes the description of human eye - it's parts, defects of human eye and their correction methods, concept of power of accommodation of human eye and care of human eye.
The eyeball is a spherical structure having 2.5 diameters. Structurally, the eyeball has three layers:- sclerotic layer (outer layer); choroid (middle layer) and retina (inner layer).
Outermost layer contains sclera and cornea
Middle layer contains choroid, ciliary body and iris.
Innermost layer consists of retina
The eyeball is a spherical structure having 2.5 diameters. Structurally, the eyeball has three layers:- sclerotic layer (outer layer); choroid (middle layer) and retina (inner layer).
Focuses an image by refracting, or bending the light rays using cornea and the lens. At the yellow spot of retina an inverted image is formed. Most of the refraction of light occurs in cornea due to its curved surface.
Normal Labour/ Stages of Labour/ Mechanism of LabourWasim Ak
Normal labor is also termed spontaneous labor, defined as the natural physiological process through which the fetus, placenta, and membranes are expelled from the uterus through the birth canal at term (37 to 42 weeks
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
for beginners, providing thorough training in areas such as SEO, digital communication marketing, and PPC training in Noida. After finishing the program, students receive the certifications recognised by top different universitie, setting a strong foundation for a successful career in digital marketing.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
1. 1
Module # 40
Camera, Eye & Spectroscopy
Camera
It is an optical instrument by which the permanent image of an
object or scenery is obtained on a sensitive screen. This image is
called photograph or picture.
Construction
A camera is basically a light proof container which consists of a
closed box blackened from inside to absorb stray light. On one
side of this box, there is a convex lens or (in costly cameras) a
system of lenses which acts as a single convex lens. On the other
side of this box, there is a sensitive film. A clear and well focussed
image of an object is formed on the film. This image is real,
inverted and diminished. There is a shutter between the film and
the lens. For sharp image of the object to be photographed, the
camera is focussed by moving its lens in and out with the help of
mechanical mount carrying the lens.
Working
A shutter of variable speed and a diaphragm with a variable
aperture controls the duration of time and quantity of light entering
the lens. Normally, the shutter is closed. It opens only for a
2. 2
fraction of a second when the button is pressed to take the
photograph. In this way, light falls on the film for a very short
interval of time after passing through the lens. The amount of light
passing through the lens should be so adjusted that it may have
proper impact on the film during which the shutter remains open.
Fig: Internal structure of Camera
Factors affecting the Image
(1) Diameter d of the aperture of the lens. It adjusts the suitable
amount of light entering the camera.
(2) Focal length f of the lens of the camera. It adjusts the area
and size of the image formed on the film.
(3) The time for the opening of shutter. It is so adjusted that the
film is exposed to the light properly.
3. 3
PIN Hole Camera
A pin-hole camera is one of the applications of rectilinear
propagation of light. It was invented to observe solar eclipses
without damaging the eye sight. It consists of a rectangular box
having a very small hole on one side and a frosted glass plate,
tracing paper or a photographic plate on the opposite side.
When a narrow pencil of rays of light coming from an object
passes through the pinhole, an inverted and real image of the
object is formed on the back of the camera. For observing a clear
image, external light is blocked by covering the box with a dark
cloth.
Human Eye
Fig: Internal Structure of Eye
4. 4
Optically speaking, the human eye operates in the same manner
as camera. The eye ball is nearly spherical in structure with a
diameter of about 2.5 cm. The eye ball consists of three layers
namely, (1) Sclera (2) Choroid (3) Retina, enclosed in a cavity
filled with fluid called the vitreous humor.
The whole structure is pulled into various positions by muscles
attached around the eyeball. The outer layer of the eyeball, the
sclera, is thick and impermeable to light rays as in the case of a
camera. But, the front part of it called the cornea is transparent.
The cornea allows the light to enter and the aperture of this
camera is determined by the pigmented middle layer of the eye
called the choroid which forms a colored curtain called the iris
which is just in front of the lens. This curtain is muscular and
when it contracts, the pupil which is an opening in the centre of
the iris enlarges and more light can enter. It contracts in bright
light and dilates in dim light. Its diameter varies from about 2 mm
in daylight to about 6 mm in darkness. Its diameter is thus
automatically adjusted to control the amount of light entering the
lens of the eye. A transparent and flexible convex lens is held just
behind the iris and its focal length can be altered by the pressure
of the ring shaped ciliary muscles surrounding it. The process of
changing the shape of the lens to see nearby or far away objects
clearly is called accommodation.
5. 5
The rays of light from an object are focussed and converged by
the lens to the sensitive internal layer of the eyeball called the
retina which is situated at the back of the eye chamber. The retina
is a nerve tissue sensitive to light. It contains over a million nerve
fibers. These fibers transmit electric signals along the optic nerves
to the brain. Although the image formed on the retina is inverted
and reversed, the brain interprets this and the images are seen
the right way up.
The shape of the eye is maintained by the pressure of colorless
transparent fluid in the eye. The fluid between the cornea and the
lens is a water-like liquid called the aqueous humor. The rest of
the eye is filled with a clear jelly-like substance known as vitreous
humor.
The farthest distance at which an eye can see objects clearly is
called the far point. The point closest to the eye at which objects
can be seen clearly is called the near point. For a normal eye, the
near point is at 25 cm. This distance is called least distance of
distinct vision.
Defects of Vision
The following are the defects of eye:
(1) Short Sightedness or Near Sightedness (Myopia).
6. 6
(2) Long Sightedness or Far Sightedness (Hypermetropia)
(3) Astigmatism
(4) Lack of Accommodation (Presbyopia)
Least Distance of Distinct Vision
The minimum distance at which an eye can see an object clearly
and distinctly is known as least distance of distinct vision. For
normal and healthy eye, this distance is about 25 cm. For children
this distance is small and it increases to 25 cm with the growing
age.
Persistence of Vision
The lingering effect of the image of an object, after it is removed,
is called persistence of vision. If an object is removed from the
seen of eye, the impression of the image persists for about I/10th
of a second in our eye. The cinema movies are made on this
principle.
Long Sightedness or Far Sightedness or Hypermetropia
If an eye is unable to see near objects but is able to see distant
objects, it is suffering from a disease known as long sightedness
or far sightedness or Hypermetropia.
7. 7
A long sighted person can see distant objects clearly but cannot
see near objects distinctly. The defect is either due to the focal
length of the eye lens being too long or the eye ball being too
short. The eye lens of such an eye is less converging. The light
rays from near objects are, therefore, focussed behind the retina
and the object is not seen clearly.
Removal of Defect
This defect of an eye can be corrected by using a convex lens of
suitable focal length in front of the eye.
In other words, the remedy or treatment for this defect is to wear
spectacles or contact lenses with convex lenses of suitable focal
lengths. These converge the light rays so that the eye lens can
focus the image clearly on the retina.
Astigmatism
If the cornea or the surface of the eye is not perfectly spherical,
then, the eye has different focal points in different planes and the
image of an object is not focussed clearly on the retina. To correct
this defect, asymmetrical lenses which have different radii of
curvature in different planes are used.
8. 8
Comparison of a Camera and an Eye
(1) The lens of a camera forms an image of the object on a
sensitive plate whereas the eye lens forms an image on the retina
of the eye.
(2) The iris and pupil of eye act similar to the shutter of a
camera and control the amount of light entering the eye.
Short Sightedness or Near Sightedness or Myopia
If an eye is unable to see distant objects but is able to see near
objects, it is suffering from a disease known as short sightedness
or near sightedness or Myopia. A short sighted person can see
near objects clearly but distant objects cannot be seen by him
clearly. This defect is either due to the focal length of the eye lens
being too short or the eye ball being too elongated. The eye lens
of such an eye is too converging. The light rays from a distant
object are, therefore, focused in front of the retina.
Removal of Defect
This defect of the eye can be corrected by using a concave lens
of suitable focal length in front of the eye.
In other words, the remedy or treatment for this defect is to wear
spectacles or contact lenses with concave lenses of suitable focal
lengths. These diverge the light rays so that the eye lens can
9. 9
focus the image clearly on the retina.
Lack of Accommodation (or Presbyopia)
At old age, the eye lens losses its elasticity and ability to change
its shape and the ciliary muscles become weak. These factors
result in a lack of accommodation. The defect called presbyopia
can be corrected by using convex leases. But, for looking at
distant objects, one will have to use concave lenses. This is the
reason why old people use spectacles having bifocal lenses, i.e.,
convex part in the lower side to see near objects and concave
part in the upper side to see the distant objects.
Fig: Bifocal Spectacles
Spectrometer
It is an optical instrument which is used to study light from
different sources or for the minute study of spectra.
Construction
It essentially consists of three parts:
(1) a collimator
(2) a telescope, and
10. 10
(3) a turn-table, as shown in the figure below:
Turntable
Levelling Screws
Fig: The Spectrometer.
The collimator C consists of a slit, the width of which can be
adjusted. It is placed at the focal plane (focus) of a convex lens L1
(as shown in figure above), so that light from the slit may become
parallel after passing through the lens. The lens and the slit are
placed at the ends of a metallic tube and the distance between
them can be altered (changed or adjusted).
The telescope is an ordinary refracting telescope fitted with cross-
wires at the focal plane of the objective lens L2. The telescope
can be rotated about the central axis of the spectrometer. The
rotation of the telescope can be read on a circular scale
graduated in degrees with the help of a vernier arrangement
Telescope
Collimator
Slit
11. 11
The turn table supporting the prism can be raised or lowered. It
can also be rotated about a vertical axis through any desired
angle. The turn table is provided with three leveling screws S1, S2
and S3.
Working
(1) The telescope is pointed towards a white wall and the eye-
piece is slowly drawn out until the cross-wires are distinctly
visible. That is, the eye-piece is focussed on the cross-wires so
that they are clearly visible.
(2) The telescope is adjusted for parallel rays so that a parallel
beam falling on the objective of the telescope produces an image
at the cross-wires.
To achieve this, parallax is removed between the image of a far
off object and the cross-wires.
(3) The telescope is turned and brought in front of the collimator.
The collimator is also adjusted to give a parallel beam of light.
This is done by illuminating the slit with mono-chromatic light
(sodium light) and viewing image of the slit through the telescope.
The distance of the slit from the collimator is adjusted till the slit is
in focus of the telescope.
The parallax is removed between the image of the slit and the
12. 12
cross-wires. When this is so, the collimator gives a parallel beam
of light.
Uses
The spectrometer is used for the determination of the refractive
index of transparent materials and also for the determination of
wavelengths of different light from different sources.
Spectroscopy
It is that branch of physics which is concerned with the
production, measurement and interpolation of electromagnetic
spectra produced by either emission or absorption of radiant
energy by various substances.
In atomic spectroscopy, we study (i) photon emission and photo
absorption spectra of atoms, and (ii) ejected-electron spectra of
atoms following electron, ion and photon impact excitation /
ionization.
Spectrum
We know that dispersion of sunlight or white light is produced with
the help of a prism and a band of red, orange, yellow, green, blue,
indigo and violet colors is observed. A band of colors formed in
this way is called a spectrum. Each color in this spectrum
represents a certain range of frequency and wave length.