Human Eye and Colourful World Full chapter (Animation) | Class 10 Science Chapter 11 | CBSE

Summary

This 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

00:00

👀 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.

05:03

👓 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.

10:04

🌈 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.

15:04

🌅 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.

Keywords

💡Human Eye

The human eye is a complex organ that functions as a light sensing organ, allowing us to perceive the world around us. In the video, it is compared to the resolution of a camera, highlighting its high resolution of approximately 576 megapixels. The eye's structure and function are central to the video's theme, which explores the mechanics of vision and how the eye captures and processes light.

💡Resolution

Resolution refers to the level of detail an image can capture, measured in megapixels. The video script mentions the human eye's resolution as 576 megapixels, a figure used to emphasize the eye's superior capability compared to the iPhone 14 Pro Max's 48 megapixels. Resolution is a key concept in understanding the eye's visual acuity and its comparison to camera technology.

💡Cornea

The cornea is a thin, transparent, and spherical membrane at the front of the eye that allows light to enter. The script describes its role in the initial step of the vision process, where light first passes through the cornea before being focused by the crystalline lens. It is an essential component of the eye's anatomy discussed in the video.

💡Crystalline Lens

The crystalline lens, also known as the eye lens, is a soft and flexible structure made of proteins that functions as a convex lens to focus images on the retina. The script explains how the lens, along with the ciliary muscles, adjusts its shape to focus on objects at varying distances, which is crucial for the eye's accommodation power.

💡Iris

The iris is a muscular diaphragm that controls the size of the pupil, the small hole through which light enters the eye. The script describes how the iris adjusts the pupil's size in response to different light conditions, thereby regulating the amount of light that enters the eye and protecting the sensitive retina.

💡Retina

The retina is a light-sensitive layer at the back of the eye that contains cells responsible for converting light into electrical signals. The script explains that these cells, known as rods and cones, are activated by light and are essential for low-light and color vision, respectively.

💡Optic Nerve

The optic nerve is responsible for transmitting the electrical signals generated by the retina to the brain, where they are interpreted as visual images. The script mentions this nerve as a critical component in the process of sight, linking the eye's light detection to the brain's visual perception.

💡Blind Spot

The blind spot is the area of the retina where the optic nerve connects to the eye, lacking the light-sensitive cells that are present elsewhere. The script notes the existence of this spot, which is a natural part of human vision but typically goes unnoticed due to the brain's ability to fill in the visual information.

💡Cataract

Cataract is a condition where the crystalline lens of the eye becomes cloudy, leading to a loss of vision. The script describes cataract as a common age-related issue that can be corrected through surgery, illustrating the importance of the lens's clarity for proper vision.

💡Defective Vision

Defective vision, or the inability to see objects distinctly and comfortably, is discussed in the script in relation to three main types of refractive errors: myopia (nearsightedness), hypermetropia (farsightedness), and presbyopia. The script explains how these conditions affect the eye's ability to focus light correctly on the retina, leading to blurred vision.

💡Refraction

Refraction is the bending of light as it passes from one medium to another, which is key to the eye's ability to focus light onto the retina. The script also discusses refraction in the context of a prism, demonstrating how light can be bent and dispersed into its constituent colors, a phenomenon relevant to the study of vision and optics.

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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