Human Eye and Colourful World Full chapter (Animation) | Class 10 Science Chapter 11 | CBSE
Summary
TLDRThis script delves into the marvels of the human eye, comparing its 576-megapixel resolution to the iPhone 14 Pro Max's 48 megapixels. It explores the eye's anatomy, from the cornea to the optic nerve, and explains the power of accommodation and common vision defects like myopia, hypermetropia, and presbyopia. The script also covers optical phenomena like refraction, dispersion, and atmospheric effects, concluding with the Tyndall effect and why red is used for danger signals, offering a comprehensive look at the colorful world we perceive.
Takeaways
- 👀 The human eye has a resolution of about 576 megapixels, which is significantly higher than the 48 megapixels of the iPhone 14 Pro Max camera.
- 🛡️ The cornea is a transparent, spherical membrane that allows light to enter the eye, while the crystalline lens focuses these images on the retina.
- 🌀 The iris controls the size of the pupil, adjusting the amount of light entering the eye based on ambient light conditions.
- 💪 Ciliary muscles alter the shape of the lens to change the eye's focal length, enabling clear vision of both distant and near objects.
- 👁️ The retina contains light-sensitive cells, which convert light into electrical signals that are transmitted to the brain via the optic nerve.
- 🌈 Defects in vision, such as myopia, hypermetropia, and presbyopia, can be corrected with lenses or surgical procedures.
- 🌌 The human eye has a horizontal field of view of about 150 degrees with one eye and approximately 180 degrees with two eyes, enhancing depth perception and clarity.
- 🌈 Light dispersion through a prism splits white light into its constituent colors, creating a spectrum, which was first demonstrated by Isaac Newton.
- 🌈 Rainbows are natural dispersion of light by raindrops, creating a spectrum opposite to that of the sun.
- 🌍 Atmospheric refraction causes stars to appear slightly higher than their actual positions and is responsible for phenomena like the twinkling of stars and the advanced sunrise.
- 🔴 Red is used for stop and danger signals because it is least scattered by fog or smoke, making it visible at longer distances.
Q & A
What is the estimated resolution of the human eye?
-The estimated resolution of the human eye is about 576 megapixels.
How does the resolution of the human eye compare to the iPhone 14 Pro Max camera?
-The human eye has a much higher resolution than the iPhone 14 Pro Max camera, which is 48 megapixels.
What are the main parts of the human eye?
-The main parts of the human eye include the cornea, iris, crystalline lens, pupil, ciliary muscles, aqueous humor, vitreous humor, retina, optic nerve, and the blind spot.
What is the function of the cornea in the human eye?
-The cornea is a thin transparent spherical membrane that covers the front part of the eye and allows light to enter the eye.
How does the iris regulate the amount of light entering the eye?
-The iris controls the size of the pupil, adjusting it to be larger in low light conditions and smaller in bright light to regulate the amount of light entering the eye.
What is the role of the ciliary muscles in vision?
-The ciliary muscles hold the lens in position and help in changing the shape of the lens, which is essential for focusing on objects at different distances.
What are the two types of light-sensitive cells in the retina, and what do they do?
-The two types of light-sensitive cells in the retina are rod cells, responsible for vision in low light, and cone cells, which are active at high light levels and help in recognizing colors.
What is the far point of the eye, and how does it differ for a normal eye and a myopic person?
-The far point of the eye is the maximum distance at which one can see clearly. For a normal eye, it is infinity, but for a myopic person, it is less than infinity, causing them to see distant objects as blurry.
What is cataract, and how can it affect vision?
-Cataract is a condition where the crystalline lens of the eye becomes milky and cloudy, causing partial or complete loss of vision. It can be corrected by cataract surgery.
What are the three main types of defective vision in humans?
-The three main types of defective vision are myopia (nearsightedness), hypermetropia (farsightedness), and presbyopia (age-related loss of the ability to focus on nearby objects).
Why do we have two eyes instead of one for vision?
-Having two eyes provides a wider field of view, better depth perception, and the ability to see faint objects more clearly, which is essential for proper vision.
Outlines
👀 The Marvel of the Human Eye
This paragraph delves into the remarkable capabilities of the human eye, which is a sophisticated light-sensing organ with a resolution estimated at 576 megapixels, surpassing the 48 megapixels of the iPhone 14 Pro Max camera. It introduces the various parts of the eye, including the cornea, iris, crystalline lens, pupil, ciliary muscles, aqueous humor, vitreous humor, retina, optic nerve, and blind spot. The paragraph explains the functions of each part, such as the cornea allowing light entry, the iris controlling pupil size to regulate light intake, and the retina's role in generating electrical signals from light-sensitive cells. It also discusses the eye's power of accommodation, the far and near points of vision, and common eye defects like cataract, myopia, hypermetropia, and presbyopia, along with their causes and corrections.
👓 Understanding Vision Defects and Light Refraction
This section explores the concept of defective vision, which occurs when the eye's power of accommodation is compromised, leading to blurry vision. It categorizes vision defects into three main types: myopia (nearsightedness), hypermetropia (farsightedness), and presbyopia. The paragraph explains the causes of these defects, such as excessive curvature of the lens or elongation of the eyeball in myopia, and either a too-long focal length of the lens or a too-small eyeball in hypermetropia. It also describes how these defects can be corrected using lenses or surgical procedures. Additionally, the paragraph introduces the refraction of light through a prism, dispersion of white light, and the historical discovery by Isaac Newton. It concludes with an explanation of how prisms and their angles affect light deviation.
🌈 Phenomena of Light and Color in the Atmosphere
This paragraph discusses various atmospheric phenomena related to light and color. It starts with the formation of a rainbow, which is a natural spectrum created by raindrops acting as small prisms to refract and disperse sunlight. The paragraph then moves on to atmospheric refraction, which causes objects near the horizon to appear higher than they are due to the bending of light as it passes through the Earth's atmosphere. It explains how this refraction affects the apparent position of stars and leads to the twinkling effect, while planets do not twinkle due to their proximity and extended disc appearance. The paragraph also covers advanced sunrise and delayed sunset phenomena, where the sun appears before and after the actual times due to atmospheric refraction. Finally, it touches on the scattering of light, responsible for the blue sky and the reddening of the sun, and the Tyndall effect, which makes suspended particles in the atmosphere visible when illuminated by light.
🌅 The Science Behind the Colors of the Sky and Sun
The final paragraph focuses on the science behind the colors we see in the sky and the sun during different times of the day. It explains why the sky appears blue during the day due to the scattering of shorter wavelength light by particles in the Earth's atmosphere. The paragraph also addresses why the sky would appear dark without an atmosphere. It further explains why red is the color of choice for stop and danger signal lights, as it is least scattered by fog or smoke and can be seen at longer distances. The explanation of the sun's color during sunrise and sunset is provided, detailing how the longer wavelengths of light reach our eyes after shorter wavelengths are scattered away by the atmosphere, resulting in the red appearance of the sun during these times. The paragraph concludes with a call to action for viewers to like, share, and subscribe to the Great Booster Channel for updates.
Mindmap
Keywords
💡Human Eye
💡Resolution
💡Cornea
💡Crystalline Lens
💡Iris
💡Retina
💡Optic Nerve
💡Blind Spot
💡Cataract
💡Defective Vision
💡Refraction
Highlights
The human eye has a resolution calculated to be about 576 megapixels, surpassing the 48 megapixels of the iPhone 14 Pro Max camera.
The structure of the human eye includes the cornea, iris, crystalline lens, pupil, ciliary muscles, aqueous humor, vitreous humor, retina, optic nerve, and blind spot.
The cornea is a transparent membrane that allows light to enter the eye.
The crystalline lens focuses images on the retina and is made of a soft, flexible jelly-like material.
The iris controls the size of the pupil, adjusting the amount of light entering the eye.
Ciliary muscles adjust the shape of the lens for focusing on objects at varying distances.
The retina contains light-sensitive cells that generate electrical signals in response to light.
There are two types of cells in the retina: rod cells for low light vision and cone cells for high light and color recognition.
The optic nerve transmits electrical signals from the retina to the brain.
The blind spot is where the optic nerve connects to the eye, without any photoreceptor cells.
Aqueous humor provides nutrition and keeps the cornea moist, while vitreous humor maintains the eye's shape.
The power of accommodation allows the eye to adjust its focal length for clear vision at different distances.
Cataract is a condition where the crystalline lens becomes cloudy, causing vision loss that can be corrected with surgery.
Having two eyes expands the field of view and improves depth perception and binocular vision.
Defective vision includes myopia, hypermetropia, and presbyopia, which affect the eye's ability to focus on objects.
Myopia, or nearsightedness, allows clear nearby vision but blurs distant objects, often corrected with concave lenses.
Hypermetropia, or farsightedness, enables clear distant vision but requires convex lenses for nearby objects.
Presbyopia is an age-related condition causing difficulty in focusing on nearby objects, often corrected with bifocal lenses.
Refraction of light through a prism demonstrates the bending of light and the dispersion of white light into a spectrum of colors.
Atmospheric refraction causes stars to appear higher than their actual position and is responsible for the twinkling effect.
The sky appears blue due to scattering of shorter wavelength light by atmospheric particles and molecules.
Red light is used for danger signals because it is least scattered by fog or smoke, maintaining visibility at longer distances.
The sun appears red during sunrise and sunset due to the scattering of shorter wavelengths, leaving longer wavelengths to reach our eyes.
Transcripts
[Music]
foreign
ful world
human eye is a light sensing organ which
helps us to see the objects around us
the resolution of human eye is
calculated about 576 megapixels the
iPhone 14 pro Max camera resolution is
48 megapixels now you can estimate how
many times the human eye is more
powerful than iPhone camera let us begin
this chapter with structure and
functions of the human eye
parts of the human eye this is cornea
this is Iris this is crystalline lens
this is pupil these are ciliary muscles
this is aqueous humor and this is
vitreous humor
this is retina
this is optic nerve and this is the
blind spot now let us study each part in
details cornea it is a thin transparent
spherical membrane covering the front
part of the eye light enters our eye
through this membrane crystalline lens
it is also called as eye lens it is a
soft and flexible jelly-like material
which is made up of proteins
it is a convex lens and helps to focus
images on the retina
iris iris is a dark muscular diaphragm
present between cornea and lens it
controls the size of the pupil
pupil it is a small hole through which
the light passes it regulates the amount
of light entering the eye when the light
is low it opens up completely to allow
more light into the eye when the light
is bright pupil becomes very small to
reduce the light that enters the eye the
contraction and relaxation of Iris
muscles adjusts the size of the pupil
ciliary muscles they hold a lens in
position and help in changing the shape
of the lens
retina
retina is a delicate membrane which
consists of numerous light sensitive
cells these light sensitive cells get
activated when light falls on them and
generate electrical signals
the light sensitive cells of the retina
or of two types one rod cells they are
responsible for vision in low light 2.
corn cells they are active at high light
levels they also help us in recognizing
the colors
optic narrow it transmits the electric
signals generated by the cells of retina
to brain
blind spot it is the place at where the
optic nerve is connected to the eye
aqueous humor the space between cornea
and lens is filled by a transparent
liquid called aqueous humor it keeps the
cornea moist and also it provides
nutrition to the eye vitreous humor the
space between the islands and retina is
filled with a liquid called vitreous
humor this vitreous humor helps the eye
to keep its shape
power of accommodation
power of accommodation is the ability of
islands to adjust its focal length the
eye lens is made up of a fibrous
jelly-like material the change in the
shape of the islands changes the
curvature of the lens the contractions
and relaxations of ciliary muscles can
modify the shape of the lens to view the
distant objects clearly the ciliary
muscles get relaxed and the lens becomes
thin then the focal length gets
increased and we can see the distant
objects clearly
to see the closer objects clearly the
ciliary muscles contract this increases
the curvature of the islands the islands
then becomes thicker and the focal
length of the islands decreases this
enables us to see nearby objects clearly
far point of the eye
maximum distance to which I Can See
Clearly is called four point of I it is
infinity for a normal eye near point of
the eye the minimum distance at which an
object can be seen clearly without any
strain is called the least distance of
distinct Vision the near point of normal
eye of an adult is 25 centimeters
cataract for some people at their old
age the crystalline lens becomes milky
and cloudy this condition is called
cataract this causes partial or complete
loss of vision this can be corrected by
a cataract surgery why we have two eyes
for vision and not just one
a human being has a horizontal field of
view of about 150 degrees with one eye
and about 180 degrees with two eyes
faint objects cannot be seen properly
with a single eye so we need a pair of
eyes for proper vision
defects of human eye what is defective
Vision when a person cannot see the
objects distinctly and comfortably it is
called as defective Vision it happens
when the power of accommodation of I is
reduced it leads to blurry vision which
causes strain to eyes the defective
vision of human eye is mainly of three
types one myopia two hypermetropia and 3
presbyopia myopia this defect of I is
called nearsightedness persons with this
defect can see the nearby objects
clearly but cannot see the four objects
clearly we learned that the normal four
point of human eye is infinite but for a
myopic person the four point is less
than the infinity in myopic persons the
Far Point will be only a few meters we
know that when the image of an object is
casted on the retina then we will be
able to see it clearly whereas in myopia
the image is casted in front of the
retina that leads to blurry vision this
can be corrected by using a concave lens
it makes the image to fall on retina so
by that the myopic person can see the
four objects clearly reasons for myopia
there are two reasons for myopia one
excessive curvature of the islands two
elongation of eyeball second one
hypermetropia this defect of eye is
called farsightedness persons with this
defect can see the four objects clearly
but cannot see the nearby objects
clearly we learned that the normal near
point of human eye is 25 centimeters but
for a hypermotropic person the near
point is farther away from 25
centimeters hypermetropic persons keeps
their reading material much Beyond 25
centimeters from the eye for comfortable
reading this is because the light rays
from a close by object are focused at a
point behind the retina this can be
corrected by using a convex lens it
makes the image to fall on retina so by
that the impersons can see the nearby
objects clearly reasons for
hypermetropia there are two reasons for
this defect this defect arises either
because one the focal length of eye lens
is too long or two the eyeball has
become too small third one press biopia
presbyopia is the gradual loss of your
eyes ability to focus on nearby objects
press biopic people find it difficult to
see nearby objects comfortably and
distinctly without corrective eyeglasses
this defect arises due to the gradual
weakening of the ciliary muscles and
diminishing flexibility of the islands
some people suffer from both myopia and
hypermetropia in such cases bifocal lens
needed for proper Vision a common type
of bifocal lenses consists of both
concave and convex lenses the upper
portion consists of a concave lens it
helps in distant Vision whereas the
lower part is a convex lens it
facilitates the near Vision these days
all the refractive defects are corrected
with contact lenses or through surgical
procedures this is about defects of
human eye refraction of light through
prism
this is a triangular prism it has two
triangular bases and three rectangular
surfaces
these surfaces are inclined to each
other
the angle between its two lateral faces
is called the angle of the prism let us
pass some laser light through this
prison at some angle the light rays get
deviated and emerges out from the other
side let us draw the normal for the
incident Ray and the emergent Ray now
this is the incident Ray this is
deviated Ray and this is the emergent
Ray
now extend the incident Ray and emergent
Ray they both meet at a point
the angle of these two rays at this
point is called the angle of deviation
dispersion of white light by glass prism
if we pass white light or sunlight
through a prism it splits into seven
colors this is called dispersion of
light
the phenomenon of splitting of white
light into its constituent colors when
it passes through a prism is called
dispersion the light rays of different
colors travel with the same speed in
vacuum and in air but in other mediums
they travel with different speeds and
bend through different angles which
leads to dispersion of light
when white light or sunlight is
dispersed we will get a band of seven
colors called spectrum of sunlight
they include violet indigo blue green
yellow orange red
simply called as web ZR Isaac Newton was
the first to split the sunlight using a
glass prism he placed his second
identical prism in an inverted position
with respect to the first one and
allowed the Spectrum to pass through it
he observed that a beam of white light
is emerged from the other side of the
second prism
rainbow rainbow is a natural Spectrum
formed by raindrops it always forms
opposite to this sunlight here the water
droplets act as small prisms when
sunlight hits the raindrops they refract
and disperse the incident sunlight then
reflect it internally and finally
refract it again when it comes out of
the raindrop atmospheric refraction
atmospheric refraction is the bending of
light as it passes through the Earth's
atmosphere causing objects near the
Horizon to appear slightly higher than
they actually are
effects of atmospheric refraction
apparent position of these Stars
the apparent position of stars refers to
their observed location in the night sky
this is the original position of this
star
but due to atmospheric refraction it
appears to be at another position which
is called as apparent position
the density of the air near the Earth is
more compared to the density of the
atmosphere towards this space
this makes the refractive index of the
atmosphere gradually increases top to
bottom due to this changing refractive
index Starlight bends towards the normal
because of this we see the star at
slightly different position from its
actual position the star appears
slightly higher than its actual position
when viewed near the horizon
twinkling of stars
the air in the atmosphere does not have
the uniform temperature and density
different regions of atmosphere will
have different refractive index due to
differences in their temperatures
the path of rays of light coming from
the Star goes on varying slightly the
apparent position of the star fluctuates
and the amount of Starlight entering the
eye flickers the Stars sometimes appear
brighter and at some other time fainter
which is the twinkling effect
then why don't planets twinkle
planets do not twinkle like stars
because they are much closer to the
Earth and appear as small extended discs
rather than a point source of light
the light coming from them consisting of
multiple points across their surface the
combined effect of these multiple Points
of Light helps to average out the
atmospheric turbulence resulting in a
steadier and less twinkling appearance
Advanced sunrise and delayed sunset when
sun rises above the Horizon it is called
as sunrise and the sun Downs below the
Horizon it is called sunset
The Horizon is the line that separates
the Earth from the sky
when this sunlight enters the atmosphere
due to atmospheric refraction it bends
and the sun becomes visible to us before
actually crossing the horizon
then we will be able to see the sun here
but this is not the actual position of
the sun it is the apparent position of
this sun
so due to atmospheric refraction the sun
is visible to us about two minutes
before the actual sunrise and about 2
minutes after the actual sunset
scattering of light
when a particle comes in the path of a
light Ray the light get reflected and
Scattered in all directions so the
reflection of light from an object in
all directions is called scattering of
light scattering is responsible for the
blue color of the sky and the reddening
of the Sun
Tyndall effect
the Earth's atmosphere is a transparent
medium in which particles like dust
smoke and Tiny water droplets are freely
suspended when a beam of light passes
through this medium it illuminates these
suspended particles and makes them
visible to us
this phenomenon was first observed by
John Tyndall hence it is named as
Tyndall effect color of the sky
sunlight is composed of spectrum of
colors with different wavelengths
these colors range from red with longer
wavelengths to Violet with short
wavelengths when sunlight enters the
Earth's atmosphere it encounters tiny
particles and molecules blue and violet
light rays have shorter wavelengths and
are scattered more by these small
particles and molecules than longer
wavelengths like red and yellow as a
result when sunlight enters the
atmosphere the blue and violet
wavelengths are scattered in all
directions by these particles causing
the sky to appear predominantly blue
during the daytime
if yacht has no atmosphere then there
would not have been any scattering then
the sky would have looked dark the sky
appears dark to the passengers who are
flying at very high altitudes Why Stop
signal and danger signal lights are red
danger signal lights are red in color
because red is least scattered light by
fog or spoke particles therefore it can
be seen in the same color even at longer
distances
that's why red light is preferred for
danger light
color of Sun at sunrise and sunset
during sunrise and sunset light from the
sun passes through a thick layer of
atmosphere and large distance before
reaching our eyes when the light enters
the atmosphere there most of the blue
light of shorter wavelength is scattered
Away by the particles of the atmosphere
and the light with longer wavelengths
like red reaches our eyes that's why the
Sun appears red during sunrise and
sunset
this is all about the human eye and the
colorful world
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