Welcome to our project dedicated to exploring the captivating spectrum of light! Get ready for a visually stunning presentation that unravels the secrets of light and its colorful journey. Our presentation offers an in-depth exploration of the spectrum of light, ranging from the familiar rainbow hues to the invisible realms beyond. Through vibrant visuals, interactive animations, and clear explanations, we guide you through the mesmerizing phenomenon of light dispersion. Discover how white light can be separated into its constituent colors, forming a beautiful spectrum. Explore the properties of each color band, from the longest wavelength red light to the shortest wavelength violet light. Learn about the wavelengths, frequencies, and energies associated with different colors. Delve into the fascinating science behind light, from the electromagnetic waves that carry it to the intricate workings of our eyes that perceive it. Understand how different materials interact with light, leading to phenomena such as reflection, refraction, and absorption. Our presentation goes beyond the visible spectrum, delving into ultraviolet (UV), infrared (IR), and other parts of the electromagnetic spectrum. Uncover the applications of these regions, from UV sterilization to IR imaging and beyond. Whether you are a student, a science enthusiast, or simply curious about the enchanting world of light, our presentation will captivate your senses and deepen your understanding. Join us on this enlightening journey as we unravel the diverse and awe-inspiring spectrum of light

1. DE V I A T I O N P R O D U C E D B Y A TR I A N G U L A R PR I S M
-When a single coloured light ray PQ enters the
triangular prism ABC it gets deviated from an angle
δ1 towards the base BC at first surface AB of the
prism and travels straight as QR inside the prism.
-The angle of deviation δ1 depends on angle of
incident and the refractive index of glass with respect
to air.
-On striking second surface AC ray QR gets further
deviated say by an angle δ2 towards the base BC
and travels as RS outside the prism.
-The angle of deviation δ 2 depends on the angle
of incidence at the second surface which depends on
the angle of the prism and the refractive index of air with
respect to glass.
-For the emergent ray RS the total deviation δ with
respect to the incident ray PQ that is the angle
between the emergent ray RS and the direction PL
δ1 + δ2 =
δ

2. Angle of Incidence
The angle of deviation first decreases,
reaches to a minimum value for a
certain angle of incidence and then on
further increasing the angle of
incidence, the angle of deviation
begins to increase.
Refractive Index Angle on Prism
It is found that for a given angle of
incidence, a prism with a higher
refractive index produces greater
deviation than a prism which has a
lower refractive index.
It is found that the Angle of Deviation
increases with the increase in the
Angle of the Prism.
FACTORS AFFECTING ANGLE OF DEVIATION

3. DEPENDENCE OF DEVIATION ON THE COLOUR OR WAVELENGTH OF LIGHT
DEPENDENCE ON COLOUR AND WAVELENGTH
COLOUR WAVELENGTH DEVIATES LEAST
RED 700–635 nm
ORANGE 635–590 nm
YELLOW 590–560 nm
GREEN 560–520 nm TO
BLUE 490–450 nm
INDIGO 440 - 450 nm
VIOLET 400 - 430 nm DEVIATES MOST
After observing this chart we can conclude that Dependence of Deviation on Wavelength is:
As wavelength decreases,the deviation of light increases and hence,deviation of light is
inversely proportional to its wavelength.

4. COLOURS IN WHITE LIGHT
Colour Wavelength Frequency
Violet 4000 A -4460 A 7.5-6.73
Indigo 4460 A-4640 A 6.73-6.47
Blue 4640 A-5000 A 6.47-6.01
Green 5000 A -5780 A 6.01-5.19
Yellow 5780 A-5920 A 5.19-5.07
Orange 5920 A- 6200 A 5.07-4.84
Red 6200 A-8000 A 4.84-3.75
The white light emitted from a source consists of lights of different
wavelengths.The light of different wavelenghts produce the sensation
of different colours on the retina of our eyes,so we percieve them as
different colours.
In the
range of
10¹⁴ Hz
Wavelength is the
characteristic of
colour,irrespective of its
origin i.e light of the same
colour obtained from
different sources will have
the same wavelength.
Colour is the subjective
property of light related to
its wavelength.

5. But μ = sin i or sin r = sin i
sin r μ
From the definition of refractive index,
μ glass = speed of light in air
speed of light in glass
The speed of light for different colours is
same in vacuum but is different for different
colours in glass. In glass, the speed of violet
light is minimum and the speed of red light is
maximum. Therefore, μ violet > μ red
Therefore, in glass, for a given value of i, the
angle of value of r is minimum for the violet
colour light and maximum for the red colour
light. Therefore, r violet > r red
Now the angle of deviation
δ = i - r, so δ violet > δ red

6. The angstrom is a unit of measurement of
length. The angstrom or ångstrom (Å) is
an internationally recognized unit of length
equal to 1 × 10-10 meters (m) or 0.1
nanometer (nm). The unit is widely used
to express the sizes of atoms, molecules,
and the electromagnetic
wavelengths.Nowadays wavelength is
expressed mostly in nanometer(nm).
In the spectrum of white
light ,red colour has the
longest wavelength 8000 Å
(or 8 x 10-7m or 800 nm) or
lowest frequency 3.75 x
1014 Hz and violet colour
has the shortest wavelength
4000Å or highest frequency
7.5 x 1014 Hz . from the
violet end to the red end of
the spectrum, the
wavelength increases while
the frequency decreases.
Annika Pillai 27

8. Newton’s Experiment
Newton allowed white light from the sun to enter a dark room through
a small aperture in a window and placed a glass prism in the path of
the light rays. The light emerging out of the prism was recieved on a
white screen. On the screen a coloured patch like that of a rainbow
was obtained which was termed spectrum.
Conclusion
From the above
experiment , Newton
concluded that white
light consists of
seven prominent
colours.Each colour
corresponds to a
small range of
wavelenght . thus ,
white light is a
mixture of large
number of
wavelenghts.
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9. What is dispersion?
It is the phenomenon of splitting of of white light by a prism
Into its constituent colours is known as dispersion
Well then what cause it ?
The cause of dispersion of white light is that lights of different
wavelengths travel with different speeds in a medium . when white light
enters the first surface of a prism ,lights of different colours due to their
difference in speeds in the glass get deviated
Through different angles towards the base of the prism
DISPERSION OF LIGHT AND SPECTRUM
Then what is a spectrum?
On passing white light through a prism ,the band of colours seen on a
screen os called a spectrum

10. Cause of dispersion of white light & Formation of Spectrum
● The cause of dispersion of white light is that lights of different wavelengths
travel with different speeds in a medium. When white light enters the first
surface of a prism, lights of different colours due to their different speeds in
glass, get deviated through different angles towards the base of the prism.
● Violet colour is deviated the most
● Red colour is deviated the least
● On the first surface of the prism splitting takes place and on the second
surface prism refraction takes place(from glass to air).
● Here again deviation takes place and as a result the colours get further
separated. The light emerging out of the prism, thus, has different colours
that spread out the most to form a spectrum on the screen.