in this ppt there is info about atmospheric refraction.info about scattering of light, rainbow formation, twinkling of stars, cause of refraction of light,laws of refraction, why the sky is blue, why the sun appears red at sunrise and at sunset, why clouds appear white are also given.

2. AKASH SHARMA
BHARAT
DANISH
HARSH RAJPUT
HARSHIT MEMORIA
ROHIT BATRA
SIDDHANT GUPTA

3. I would like to thank my Science teacher
Shalini Mam and my group members for
helping me in making this presentation. My
group members helped me in editing of this
presentation. My parents helped me in
formatting the matter of the presentation.
I collected the information from the
internet and from some books.My other
gratitude I would like to convey to my
school who suggest me to make this and to
have marks for adding it into examination.

4. REFRACTION
CAUSES OF REFRACTION
LAWS OF REFRACTION OF LIGHT
ATMOSPHERIC REFRACTION
TWINKLING OF STARS
ADVANCED SUNLIGHT AND DELAYED SUNSET
RAINBOW FORMATION
SCATTERING OF LIGHT
WHY THE SKY IS BLUE
WHY THE SUN APPEARS RED AT SUNRISE AND SUNSET
WHY THE CLOUDS APPEAR WHITE

5. The change in the direction of light when it
passes from one medium to another, is called
Refraction of light.
In other words, the bending of light when it
goes from one medium to another obliquely is
called Refraction of light-

6. CAUSE OF REFRACTION OF LIGHT
The refraction of light is due to the
change in the speed of light on going from
one medium to another.
Greater the difference in the speeds of
light in the two media, greater will be the
amount of refraction of light.

7. LAWS OF REFRACTION
The refraction of light on going from one medium
to another takes place from one medium to
another takes place according to two laws which
are known as Laws of Refraction. These are:-
The incident ray, the normal ray, and the point
of incidence, all lie in the same plane.
The ratio of sine of incidence to the sine of
refraction is a constant for the light of a given
colour and for the given pair of media. This is
also known as Snell’s Law of refraction.
If i is angle of incidence and r is the angle of
refraction, then
Sin i/ sin r = constant

8. ATMOSPHERIC
REFRACTION
In the Atmosphere we have several layers having different optical densities.
The refraction of light caused by earth’s atmosphere having layers of air of
varying optical densities is called Atmospheric Refraction.

9. The twinkling of stars is due to the atmospheric refraction
of star’s light.
When the light coming from a star enters the earth’s
atmosphere, It undergoes refraction due to the varying
optical densities of air at various altitudes. The
continuously changing atmosphere refracts the light from
the stars by different amounts from one moment to the
next. The star light reaching our eyes increases and
decreases continuously due to atmospheric refraction.
And the star appears to twinkle at night.

10. When the sun is slightly below the horizon, then the
sun’s light coming from less dense air to more dense
air is refracted downwards as it passes to the
atmosphere. Because of this atmospheric refraction,
the sun appears to be raised above the horizon when
actually it is below the horizon. The same is in the
case of delayed sunset.
It is due to the atmospheric
refraction, we see the sun for
4 minutes extra.

11. The raindrops in the
atmosphere act like many
small prisms. When
sunlight enters a rain
drop, it refracts inside the
drop. Then it strikes the
boundary between two
media (which is known as
total internal reflection)
and disperses. This light
is reflected off backside
of raindrop at critical
angle. It takes many
different raindrops to
produce a rainbow.

12. Scattering of light occurs when light is
deflected in all directions. Scattering
of light occurs when light bounces on
colloidal particle and particles large
than colloidal particles. It is also called
Tyndall effect. Blue skies and red suns
are due to scattering of light.

13. The sunlight is made up of seven colours.
When sunlight passes through the
atmosphere, most of the lightsof longer
wavelengthssuch as red, yellow, orange etc.
present in it do not scattered much by air
moleculesand hence pass straight through.
However the shorter wavelengthsscattered
all around the sky by air molecules in the
atmosphere.
That is why the sky appearsblue.

14. The sun and the
surrounding sky
appear red at
sunrise and sunset
because at that
time most of the
blue colour has
been scattered
out and away

15. WHY THE CLOUDS APPEAR WHITE
When the particles are large, the
scattering of light cause the
particles to be look as white.
Some light penetrates to cloud
base and white light is scattered
in all directions.
That is why cloud appears as
white