The human eye functions like a camera, with light entering through the cornea and being focused onto the retina by the lens. The retina converts the image into electrical signals which are sent to the brain. The lens allows for accommodation by changing shape to focus on near and far objects. Common vision defects include myopia, hyperopia, and presbyopia, which can be corrected using lenses. When white light passes through a prism it is dispersed into a spectrum due to differing refraction of different wavelengths. Atmospheric effects include refraction causing twinkling stars and delayed sunsets, and scattering of blue light making the sky appear blue.
LIGHT-HUMAN EYE AND THE COLOURFUL WORLD.ppt.pptxMRMATHSACADEMY1
The document summarizes key aspects of how the human eye works and vision. It discusses the structure of the eye and how light enters and forms an image on the retina. It describes accommodation and near and far points of the eye. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections. The document also covers refraction of light through prisms and the dispersion and recombination of white light. Additional topics include rainbow formation, atmospheric refraction, scattering of light, and why the sky appears blue.
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 .
The document discusses various parts of the human eye including the cornea, iris, pupil, lens, ciliary muscles, retina, vitreous humour, and blind spot. It describes the power of accommodation and how the eye focuses on near and far objects. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections using lenses. The document also discusses the dispersion of white light through a prism, rainbow formation through water droplets, atmospheric refraction effects, scattering of light including why the sky appears blue, and the reddish color of the sun during sunrise and sunset.
Here are the answers to the questions:
1. (i) Focal length = 1/Power = 1/-5.5 dioptres = -18 cm.
(ii) Focal length = 1/Power = 1/+1.5 dioptres = +67 cm.
2. The eye is myopic. A concave lens of power -1.25 dioptres is required.
3. A convex lens is used to correct hypermetropia. The required power is 1/0.25 - 1/1 = +2 dioptres.
4. The ciliary muscles of the normal eye lose their power of accommodation for close vision beyond 25 cm.
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
The document discusses the structure and function of the human eye. It describes the eye as similar to a camera, with components like the cornea, iris, lens, retina, and vitreous humor working together to allow vision. Light enters through the cornea and is focused by the lens onto the retina. The iris controls the size of the pupil to regulate the amount of light. Common vision defects like myopia and hyperopia are also discussed as well as how they can be corrected.
The document summarizes key aspects of the human eye and vision. It describes the main parts of the eye - pupil, iris, lens, retina - and how they work together to form images. It also discusses common vision defects like myopia and hyperopia, and how they are corrected using lenses. The document further explains phenomena like dispersion of light by prisms, rainbow formation, atmospheric refraction causing twinkling of stars and the blue color of the sky.
LIGHT-HUMAN EYE AND THE COLOURFUL WORLD.ppt.pptxMRMATHSACADEMY1
The document summarizes key aspects of how the human eye works and vision. It discusses the structure of the eye and how light enters and forms an image on the retina. It describes accommodation and near and far points of the eye. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections. The document also covers refraction of light through prisms and the dispersion and recombination of white light. Additional topics include rainbow formation, atmospheric refraction, scattering of light, and why the sky appears blue.
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 .
The document discusses various parts of the human eye including the cornea, iris, pupil, lens, ciliary muscles, retina, vitreous humour, and blind spot. It describes the power of accommodation and how the eye focuses on near and far objects. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections using lenses. The document also discusses the dispersion of white light through a prism, rainbow formation through water droplets, atmospheric refraction effects, scattering of light including why the sky appears blue, and the reddish color of the sun during sunrise and sunset.
Here are the answers to the questions:
1. (i) Focal length = 1/Power = 1/-5.5 dioptres = -18 cm.
(ii) Focal length = 1/Power = 1/+1.5 dioptres = +67 cm.
2. The eye is myopic. A concave lens of power -1.25 dioptres is required.
3. A convex lens is used to correct hypermetropia. The required power is 1/0.25 - 1/1 = +2 dioptres.
4. The ciliary muscles of the normal eye lose their power of accommodation for close vision beyond 25 cm.
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
The document discusses the structure and function of the human eye. It describes the eye as similar to a camera, with components like the cornea, iris, lens, retina, and vitreous humor working together to allow vision. Light enters through the cornea and is focused by the lens onto the retina. The iris controls the size of the pupil to regulate the amount of light. Common vision defects like myopia and hyperopia are also discussed as well as how they can be corrected.
The document summarizes key aspects of the human eye and vision. It describes the main parts of the eye - pupil, iris, lens, retina - and how they work together to form images. It also discusses common vision defects like myopia and hyperopia, and how they are corrected using lenses. The document further explains phenomena like dispersion of light by prisms, rainbow formation, atmospheric refraction causing twinkling of stars and the blue color of the sky.
The human eye contains several key structures that work together to allow vision. Light enters through the cornea and passes through the pupil, which regulates the amount of light entering the eye. The light then passes through the lens, which focuses the light, and through the vitreous humour to the retina at the back of the eye. The retina converts the light image into electrical signals that are transmitted through the optic nerve to the brain for processing into vision. Common vision defects like myopia and hyperopia can be corrected using lenses that compensate for issues with the eye's focusing ability.
The document summarizes key aspects of the human eye and vision. It describes the structure of the eye, including the cornea, iris, pupil, lens, retina, and other parts. It explains how the iris controls the size of the pupil to regulate the amount of light entering the eye. It also discusses refractive errors like myopia and hyperopia, and how lenses are used to correct vision. Prisms and dispersion of light are described. Atmospheric effects like refraction, twinkling of stars, and why the sky appears blue are summarized.
Human Eye and the Colorful world notes.docxSouravMaity79
The document summarizes key aspects of vision and the human eye. It describes the main parts of the eye and their functions, including the retina, cornea, lens, iris, pupil, and optic nerve. It also discusses common vision conditions like myopia, hyperopia, presbyopia, and cataracts. The phenomenon of dispersion and the formation of rainbows are also summarized.
The document discusses various parts of the human eye including the cornea, iris, pupil, lens, ciliary muscles, retina, vitreous humour, and blind spot. It describes the power of accommodation and how the eye focuses on near and far objects. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections using lenses. The document also discusses dispersion and scattering of light through the atmosphere and prisms, including causes of rainbows, twinkling stars, and the blue color of the sky.
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.
For more information, visit-www.vavaclasses.com
This document discusses the structure and functioning of the human eye. It begins by acknowledging those who provided guidance and support. It then provides details on the various parts of the eye, including the cornea, iris, lens, retina and optic nerve. It explains how light enters the eye and is focused on the retina to produce an image. The document also discusses color vision, accommodation, defects like myopia and hypermetropia, and optical phenomena like refraction and mirages.
The document discusses various topics related to light and vision including:
1. The structure and parts of the human eye including the cornea, iris, pupil, lens, retina, and more.
2. Vision defects like myopia, hypermetropia, and presbyopia and their corrections using lenses.
3. Refraction of light through prisms and lenses, dispersion, and rainbow formation.
4. Atmospheric effects like refraction causing mirages, twinkling of stars, and scattering of light making the sky appear blue.
The document summarizes key aspects of how the human eye works and the science of light scattering. It describes the basic anatomy of the eye, including the cornea, iris, pupil, lens, and retina. It explains how the lens focuses light onto the retina and how visual signals are sent to the brain. Accommodation of the eye allows it to focus on near and far objects. Scattering of light causes the sky to appear blue and the sun red at sunrise/sunset due to the scattering of shorter wavelengths. Clouds appear white because water droplets scatter all light wavelengths.
This document discusses various optical phenomena including the nature of light, reflection, refraction, dispersion, scattering, lenses, the human eye, vision defects, microscopes, and telescopes. It explains that light travels in a straight line and can be reflected or refracted at the interface between two media. It also describes Snell's law of refraction and defines terms like refractive index. Additionally, it provides details about the structure and functioning of the human eye, common vision problems like myopia and presbyopia, and how lenses and microscopes form magnified images.
Light prepared by Yasir Khan.
Topic covered :- reflection, laws of reflection, types of images, refraction, multiple images, kaleidoscope, dispersion of light, human eye, defects of vision, cataract, care for eye.
Thank you.
The human eye functions similar to a camera, with light entering through the pupil and being focused by the cornea and lens onto the retina. The retina contains rod and cone cells that allow for vision and color perception. As light enters the eye, the iris adjusts the size of the pupil to regulate the amount of light. Various eye conditions exist such as nearsightedness, farsightedness, and cataracts that affect vision by changing the eye's ability to focus light properly.
Human Eye and Colorful World. Chapter 11 grade 10thMurari Parashar
The document summarizes key aspects of the human eye and vision. It discusses the parts of the eye like the cornea, iris, pupil, lens, retina and how they enable vision. It explains phenomena like rainbow formation, twinkling of stars and the blue color of the sky through refraction, dispersion and scattering of light. It also covers defects in vision like myopia, hypermetropia, presbyopia and their corrections using lenses.
light class 8 developed by dsv teachers DhatriBhat
The document discusses various topics related to light and vision, including:
1. What makes things visible includes light reacting with surroundings and the human eye detecting wavelengths of visible light.
2. Laws of reflection define that the angle of reflection equals the angle of incidence. Regular reflection occurs from smooth surfaces while irregular reflection occurs from rough surfaces.
3. The Braille system allows visually impaired persons to read and write through raised dot patterns representing letters and numbers that can be read by touch.
This document provides information about optics and optical instruments. It discusses how light travels in a straight line and the basic properties of light. It describes Snell's law of refraction and the dispersion and scattering of light. The document also discusses the structure of the human eye and common vision defects. Additionally, it provides details about simple microscopes, compound microscopes, telescopes, and their uses. The key points covered are the properties of light, refraction through lenses, vision defects, and applications of optical instruments like microscopes and telescopes.
The human eye structure contains several key parts that allow us to see the colorful world around us. The cornea allows light to enter the eye and the iris controls the size of the pupil to regulate light levels. The retina is where images are formed and contains rod and cone cells that detect light intensity and color. The lens, with help from ciliary muscles, focuses images onto the retina for clear vision at various distances. Common eye defects like myopia and hypermetropia result from issues with the lens and shape of the eyeball.
Light - Reflection and Refraction, Class X, CBSE, ScienceDevesh Saini
PowerPoint Presentation covering all the concepts and topics of the chapter : Light- Reflection and Refraction of class X (CBSE).
This is exactly what you are looking for.
Don't forget to comment and give feedback.
This document summarizes key concepts about light and the human eye:
1. It explains how a glass prism refracts and disperses white light into a spectrum of colors due to different wavelengths of light traveling at different speeds.
2. Rainbows are caused by the dispersion and internal reflection of sunlight within water droplets in the atmosphere, which act like prisms.
3. Atmospheric refraction makes stars appear to twinkle and causes advanced sunrise/delayed sunset by bending light through the atmosphere.
4. The scattering of blue light by air molecules is why the sky appears blue, and why the sun looks redder at sunrise/sunset when light travels through more atmosphere.
Light is a type of electromagnetic radiation that travels in waves. It can come from natural or artificial sources and travels in straight lines at a speed of about 300,000 km/s in a vacuum. Light has properties of propagation in straight lines, reflection off surfaces, and refraction when passing between different mediums. Shadows are formed when an opaque object blocks light, and solar and lunar eclipses occur due to the alignment of the sun, moon, and earth. The human eye can see visible light, but defects like myopia, hypermetropia, and astigmatism affect vision.
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The human eye contains several key structures that work together to allow vision. Light enters through the cornea and passes through the pupil, which regulates the amount of light entering the eye. The light then passes through the lens, which focuses the light, and through the vitreous humour to the retina at the back of the eye. The retina converts the light image into electrical signals that are transmitted through the optic nerve to the brain for processing into vision. Common vision defects like myopia and hyperopia can be corrected using lenses that compensate for issues with the eye's focusing ability.
The document summarizes key aspects of the human eye and vision. It describes the structure of the eye, including the cornea, iris, pupil, lens, retina, and other parts. It explains how the iris controls the size of the pupil to regulate the amount of light entering the eye. It also discusses refractive errors like myopia and hyperopia, and how lenses are used to correct vision. Prisms and dispersion of light are described. Atmospheric effects like refraction, twinkling of stars, and why the sky appears blue are summarized.
Human Eye and the Colorful world notes.docxSouravMaity79
The document summarizes key aspects of vision and the human eye. It describes the main parts of the eye and their functions, including the retina, cornea, lens, iris, pupil, and optic nerve. It also discusses common vision conditions like myopia, hyperopia, presbyopia, and cataracts. The phenomenon of dispersion and the formation of rainbows are also summarized.
The document discusses various parts of the human eye including the cornea, iris, pupil, lens, ciliary muscles, retina, vitreous humour, and blind spot. It describes the power of accommodation and how the eye focuses on near and far objects. Common vision defects like myopia, hypermetropia, and presbyopia are explained along with their corrections using lenses. The document also discusses dispersion and scattering of light through the atmosphere and prisms, including causes of rainbows, twinkling stars, and the blue color of the sky.
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.
For more information, visit-www.vavaclasses.com
This document discusses the structure and functioning of the human eye. It begins by acknowledging those who provided guidance and support. It then provides details on the various parts of the eye, including the cornea, iris, lens, retina and optic nerve. It explains how light enters the eye and is focused on the retina to produce an image. The document also discusses color vision, accommodation, defects like myopia and hypermetropia, and optical phenomena like refraction and mirages.
The document discusses various topics related to light and vision including:
1. The structure and parts of the human eye including the cornea, iris, pupil, lens, retina, and more.
2. Vision defects like myopia, hypermetropia, and presbyopia and their corrections using lenses.
3. Refraction of light through prisms and lenses, dispersion, and rainbow formation.
4. Atmospheric effects like refraction causing mirages, twinkling of stars, and scattering of light making the sky appear blue.
The document summarizes key aspects of how the human eye works and the science of light scattering. It describes the basic anatomy of the eye, including the cornea, iris, pupil, lens, and retina. It explains how the lens focuses light onto the retina and how visual signals are sent to the brain. Accommodation of the eye allows it to focus on near and far objects. Scattering of light causes the sky to appear blue and the sun red at sunrise/sunset due to the scattering of shorter wavelengths. Clouds appear white because water droplets scatter all light wavelengths.
This document discusses various optical phenomena including the nature of light, reflection, refraction, dispersion, scattering, lenses, the human eye, vision defects, microscopes, and telescopes. It explains that light travels in a straight line and can be reflected or refracted at the interface between two media. It also describes Snell's law of refraction and defines terms like refractive index. Additionally, it provides details about the structure and functioning of the human eye, common vision problems like myopia and presbyopia, and how lenses and microscopes form magnified images.
Light prepared by Yasir Khan.
Topic covered :- reflection, laws of reflection, types of images, refraction, multiple images, kaleidoscope, dispersion of light, human eye, defects of vision, cataract, care for eye.
Thank you.
The human eye functions similar to a camera, with light entering through the pupil and being focused by the cornea and lens onto the retina. The retina contains rod and cone cells that allow for vision and color perception. As light enters the eye, the iris adjusts the size of the pupil to regulate the amount of light. Various eye conditions exist such as nearsightedness, farsightedness, and cataracts that affect vision by changing the eye's ability to focus light properly.
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The document summarizes key aspects of the human eye and vision. It discusses the parts of the eye like the cornea, iris, pupil, lens, retina and how they enable vision. It explains phenomena like rainbow formation, twinkling of stars and the blue color of the sky through refraction, dispersion and scattering of light. It also covers defects in vision like myopia, hypermetropia, presbyopia and their corrections using lenses.
light class 8 developed by dsv teachers DhatriBhat
The document discusses various topics related to light and vision, including:
1. What makes things visible includes light reacting with surroundings and the human eye detecting wavelengths of visible light.
2. Laws of reflection define that the angle of reflection equals the angle of incidence. Regular reflection occurs from smooth surfaces while irregular reflection occurs from rough surfaces.
3. The Braille system allows visually impaired persons to read and write through raised dot patterns representing letters and numbers that can be read by touch.
This document provides information about optics and optical instruments. It discusses how light travels in a straight line and the basic properties of light. It describes Snell's law of refraction and the dispersion and scattering of light. The document also discusses the structure of the human eye and common vision defects. Additionally, it provides details about simple microscopes, compound microscopes, telescopes, and their uses. The key points covered are the properties of light, refraction through lenses, vision defects, and applications of optical instruments like microscopes and telescopes.
The human eye structure contains several key parts that allow us to see the colorful world around us. The cornea allows light to enter the eye and the iris controls the size of the pupil to regulate light levels. The retina is where images are formed and contains rod and cone cells that detect light intensity and color. The lens, with help from ciliary muscles, focuses images onto the retina for clear vision at various distances. Common eye defects like myopia and hypermetropia result from issues with the lens and shape of the eyeball.
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PowerPoint Presentation covering all the concepts and topics of the chapter : Light- Reflection and Refraction of class X (CBSE).
This is exactly what you are looking for.
Don't forget to comment and give feedback.
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1. CHAPTER - 11
THE HUMAN EYE AND THE
COLOURFUL WORLD
Class :- X
Subject :- Science
Name of Teacher :- Mr. V. K. Pathak (PGT Phy)
School :- KV RRL Jorhat, Assam
3. 1a) The human eye :-
The human eye is the sense organ which helps us to see the
colourful world around us.
The human eye is like a camera. Its lens system forms an image on
a light sensitive screen called retina. The eye ball is almost spherical
in shape with a diameter of about 2.3cm. Light enters the eye through a
transparent membrane called cornea. Behind the cornea is a muscular
diaphragm called iris which has an opening called pupil. The pupil
controls the amount of light entering the eye. The eye lens helps to
focus the image of objects on the retina. The ciliary muscles helps to
change the curvature of the lens and to change its focal length.
b) Working of the eye :-
The eye lens forms a real inverted image of the object on the
retina. The light sensitive cells in the retina then produce electrical
signals which are carried by the optic nerves to the brain. The brain
processes the information and sends the message to the eye and then
we see the object.
4. c) Power of accomodation of the eye :-
The ability of the eye lens to see both near and distant objects by
adjusting its focal length is called the power of accommodation of the
eye.
The eye lens is composed of a fibrous jelly like material. Its curvature
can be changed to some extent by the ciliary muscles. The change in
the curvature of the eye lens can change its focal length. When the
muscles are relaxed, the lens becomes thin and its focal length
increases and when the muscles contract, the lens becomes thick and
its focal length decreases.
d) Near point :-
The minimum distance at which the eye can see objects clearly is
called the near point or least distance of distinct vision. For a normal
eye it is 25cm.
e) Far point :-
The farthest distance upto which the eye can see objects clearly is
called the far point of the eye. For a normal eye it is between 25cm and
infinity.
5. 2) Defects of vision and their correction :-
i) Myopia or near sightedness :-
Myopia is a defect of vision in which a person can see nearby
objects clearly but cannot see distant objects clearly because the
image is formed in front of the retina.
This may be due to:-
i) Increase in curvature of the eye lens
ii) Increase in the length of the eye ball
It can be corrected by using suitable concave lens.
Myopic eye
Correction using concave lens
6. ii) Hypermetropia or far sightedness :-
Hypermetropia is a defect of vision in which a person can see
distant objects clearly but cannot see nearby objects clearly
because
the image is formed behind the retina.
This may be due to:-
i) Decrease in curvature of eye lens
ii) Decrease in the length of the eye ball
It can be corrected by using a suitable convex lens.
Hypermetropic eye
Correction using convex lens
7. iii) Presbyopia :-
Presbyopia is a defect of vision in old people in
which they are not able to see nearby objects clearly due
to the increase in the distance of near point.
This is due to the weakening of the ciliary muscles
and decrease in the flexibility of the eye lens. It can be
corrected by using suitable convex lens.
Sometimes they are not able to see both nearby and
distant objects clearly. It can be corrected by using
bifocal lenses consisting of both concave and convex
lenses. The upper part is concave for correction of
distant vision and the lower part is convex for correction
of near vision.
8. 4) Refraction of light through a glass prism :-
When a ray of light passes through a glass prism, it gets
bent twice at the air- glass interface and glass- air interface.
The emergent ray is deviated by an angle to the incident
ray.This angle is called the angle of deviation.
Incident ray
Refracted ray
Emergent ray
D
i
r
Air Glass Glass Air
Glass prism
e Angle of emergence
Angle of deviation
Normal
9. 5a) Dispersion of white light by a glass prism :-
When a beam of white light is passed through a glass
prism, it is split up into a band of colours called spectrum.
This is called dispersion of white light. The spectrum of
white has the colours violet, indigo, blue, green, yellow,
orange and red (VIBGYOR). The red light bends the least
and the violet light bends the most.
Beam of white light
Spectrum
R
O
Y
G
I
B
V
Glass prism
10.
11. b) Recombination of the spectrum of white light
produces white light :-
R
V
V
R R
When a beam of white light is passed through a glass
prism, it is split up into its component colours. When these
colours are allowed to fall on an inverted glass prism it
recombines to produce white light.
V
White light
White light
Glass prisms
12. c) Rainbow formation :-
A rainbow is a natural spectrum appearing in the sky
after a rain shower. It is caused by the dispersion of
sunlight by water droplets present in the atmosphere. The
water droplets act like small prisms. They refract and
disperse the sunlight then reflect it internally and finally
refract it again when it comes out of the rain drops. Due to
the dispersion of sunlight and internal reflection by the
water droplets we see the rainbow colours.
Sunlight
Raindrop
Red Violet
Refraction and dispersion
Internal reflection
Observer
Refraction
13.
14. 6) Atmospheric refraction :-
Atmospheric refraction is due to the gradual change in
the refractive index of the atmosphere. The refractive index
of the atmosphere gradually increases towards the surface
of the earth because the hot air above is less dense than
the cool air below. So light gradually bends towards the
normal. So the real position of a star is different from its
apparent position.
Apparent position
Real position
Eye
Star
Increasing
refractive index
of atmosphere
15.
16. i) Twinkling of stars :-
The twinkling of stars is due to the atmospheric refraction
of star light and due to the changing in the position of the
stars and the movement of the layers of the atmosphere.
So the light from the stars is sometimes brighter and
sometimes fainter and it appears to twinkle.
Planets are closer to the earth than stars. The light from
stars are considered as point source of light and the light
from planets are considered as extended source of light.
So the light from the planets nullify the twinkling effect.
17.
18. Earth
Observer
Sunrise
Sunset
Apparent position
Apparent position
Atmosphere
ii) Advance sunrise and delayed sunset :-
The sun is visible to us about 2 minutes before sunrise
and about two minutes after sunset due to atmospheric
refraction.
The apparent flattening of the sun’s disc at sunrise and
at sunset is also due to atmospheric refraction.
Horizon Horizon
Real position Real position
19. 7) Scattering of light :-
i) Tyndall effect :-
When a beam of light passes through a colloidal solution, the path
of light becomes visible due to the scattering of light by the colloid
particles. This is known as Tyndall effect.
The earth’s atmosphere contains air molecules, water droplets, dust,
smoke etc. When sunlight passes through the atmosphere the path of
the light becomes visible due to the scattering of light by these
particles.
The colour of the scattered light depends upon the size of the
scattering particles. Very fine particles scatter blue light. Larger
particles scatter different colours of light.
20.
21. ii) Why is the colour of the clear sky blue ?
The fine particles in the atmosphere have size smaller
than the wave length of visible light. They can scatter blue
light which has a shorter wave length than red light which
has a longer wave length. When sunlight passes through
the atmosphere, the fine particles in the atmosphere scatter
the blue colour more strongly than the red and so the sky
appears blue.
If the earth had no atmosphere there would not be any
scattering of light and the sky would appear dark. The sky
appears dark at very high altitudes.
22.
23. iii) Colour of the sky at sunrise and sunset :-
At sunrise and at sunset the sun is near the horizon and
the light from the sun travels through the thicker layers of
the atmosphere and longer distance through the
atmosphere. Near the horizon most of the blue light and
shorter wave lengths are scattered away by the particles of
the air and the red light and longer wave lengths reaches
our eyes. So the sun appears reddish at sunrise and sunset.
Observer
Sun near horizon
Sun overhead
Blue light scattered away
Sun appears reddish
Atmosphere
Earth