HOLY INNOCENTS PUBLIC SCHOOL
(Affiliated to the Central Board of Secondary Education, New Delhi 930877)
School Code No: 75844
PROJECT REPORT ON
PHYSICS
(2024 - 2025)
A PROJECT ON PHYSICS SUBMITTED AS PART OF
CLASS XII EXAMINATION
OF THE CENTRAL BOARD OF SECONDARY EDUCATION,
DELHI.
By:
CBSE Register No: External Examiner:
Certified Bonafide: Teacher in charge:
Principal:
ACKNOWLEDGEMENT
I would like to thank my physics teacher Mrs. Nimy for her constant
guidance, motivation, moral encouragement and sympathetic attitude
towards the success of this project. I also want to thank the principal who
provided me with many necessities. I would also like to extend my
gratitude towards the lab attendant, my parents and everyone who has
helped me in completing the project successfully. Lastly, I am grateful to
the institution for providing the necessary resources and facilities to
conduct this research. The collective efforts and contributions of all these
individuals have been pivotal in the successful completion of this project,
and I am profoundly thankful for their support. This project is a testament
to the power of teamwork and the importance of a supportive academic
community.
Once again thanking you all!
INDEX
1. INTRODUCTION
2. AIM
3. APPARATUS REQUIRED
4. THEORY
5. PROCEDURE
6. DIAGRAM
7. OBSERVATION
8. RESULT
9. PRECAUTIONS
10. SOURCES OF ERRORS
11. CONCLUSION
12. BIBLIOGRAPHY
INTRODUCTION
In optics, a prism is a transparent optical element with flat, polished surfaces
that refracts light. The exact angles between the surfaces depend on the
application. The traditional geometrical shape is that of a triangular prism with
a triangular base and rectangular sides, and in daily use "prism" usually refers
to this type. Some types of optical prism are not in fact in the shape of
geometric prisms. Prisms can be made from any material that is transparent to
the wavelengths for which they are designed. Typical materials include glass,
plastic and fluorite. Prism can be used to break light up into its constituent
spectral colours (the colours of the rainbow). Prisms can also be used to reflect
light, or to split light into components with different polarizations.
Before Isaac Newton, it was believed that white light was colourless, and that
the prism itself produced the colour. Newton's experiments demonstrated that
all the colours already existed in the light in a heterogeneous fashion, and that
'corpuscles" (particles) of light were fanned out.
Because particles with different colours travelled with different speeds
through the prism. It was only later that Young and Fresnel combined
Newton's particle theory with Huygens' wave theory to show that colour is the
visible manifestation of light's wavelength. Newton arrived at his conclusion by
passing the red colour from one prism through second prism and found the
colour unchanged. From this, he concluded that the colours must already be
present in the incoming light and white light consists of a collection of colours.
As the white light passes through the triangular prism, the light separates into
the collection of colours: red, orange, yellow, green, blue, indigo and violet.
This collection of colours formed by the prism is called the spectrum. The
separation of white light into its spectrum is known as dispersion.
Dispersion occurs because each colour travels through the prism at different
speeds. Violet travels the slowest through the prism; hence we can see it
refracting the most. On the other hand, red passes through at a much fast rate
which makes its angle of refraction less, hence red is too scarce to be seen.
EXPERIMENT TO PROVE THE DEPENDENCE OF
ANGLE OF DEVIATION ON ANGLE OF INCIDENCE
AIM:
To investigate the dependence of the angle of deviation on the angle of
incidence using a hollow prism filled with different transparent fluids.
APPARATUS REQUIRED:
Drawing board, white sheets of paper prism drawing pins, pencil, half meter
scale, thump pins, graph papers and a protractor.
THEORY:
When a ray of light passes through a prism,
Angle of prism + Angle of deviation = Angle of incidence + Angle of emergence
i.e., A+D=i+e
As i increases, D first decreases, becomes minimum and then increases. In the
position of minimum deviation Dm, the ray of light passes symmetrically,
i.e., parallel to the base so that, i = e, r1 =r2
Relation between refractive index and angle of minimum deviation,
( )
Refractive Index, n =
PROCEDURE
1. A white sheet of paper was fixed on the drawing board with the help of
drawing pins.
2. A straight line XXI parallel to the length of the paper was drawn nearly in
the middle of the paper.
3. Points Q1, Q2, Q3 and Q4 were marked on the straight line XX at suitable
distances of about 6cm.
4. Normals N1Q1, N2Q2, N3Q3 and N4Q4 were drawn on points Q1, Q2, Q3 and
Q4.
5. Straight lines R1Q1, R2Q2, R3Q3 and R4Q4 were drawn making angles of
40 , 45 , 50° and 55° respectively with the normals.
6. One corner of the prism was marked as A and it was taken as the edge of
the prism for all the observations.
7. Prism with its refracting face AB was put in the line XX’ and point Q1 was
put in the middle of AB.
8. The boundary of the prism was marked.
9. Two pins P1 and P2 were fixed vertically on the line R1Q1 and the distance
between the pins were about 2cm.
10. The images of points P1 and P2 were looked through face AC.
11. Left eye was closed and right eye was opened and was brought in line
with the two images.
12. Two pins P3 and P4 were fixed vertically at about 2cm apart such that
the open right eye sees pins P4 and P3 as images of P2 and P1 in one
straight line.
13. Pins P1, P2, P3 and P4 were removed and their pricks on the paper were
encircled.
14. Steps 7 to 13 were again repeated with points Q2, Q3 and Q4 for i= 45 ,
50 and 55 .
15. Straight lines through points P4 and P3 were drawn to obtain emergent
rays S1T1, S2T2, S3T3 and S4T4.
16. T1S1, T2S2, T3S3 and T4S4 were produced inward in the boundary of the
prism to meet produced incident rays R1Q1, R2Q2, R3Q3 and R4Q4 at
points F1, F2, F3 and F4.
17. Angles K1F1S1, K2F2S2, K3F3S3 and K4F4S4 were measured. These angles
give angle of deviation D1, D2, D3 and D4.
18. Values of these angles were written on the paper.
19. Angle BAC was measured in the boundary of the prism.
This gives angle A.
20. Observations were recorded.
OBSERVATION
Angle of hollow prism A= 60
S.No. Angle Angle Angle Angle of
of incidence of deviation of deviation for deviation for
for water kerosene oil turpentine oil
1. 40 25 36 36
2. 45 24 33 33
3. 50 25 34 34
4. 55 26 35 35
RESULTS
As the angle of incidence increases, the angle of deviation first
decreases, reaches a minimum value and then again increases.
The angle of minimum deviation for
Water Dm = 23°C
Kerosene oil Dm = 33°C
Turpentine oil Dm = 32°C
The refractive indices of
Water n=1.32
Kerosene oil n = 1.46
Turpentine oil n = 1.44
PRECAUTIONS
The angle of incidence should lie between 35 – 60 .
The pins should be fixed vertical.
The distance between the two pins should not be less than
10mm.
Arrow heads should be marked to represent the incident and
emergent rays.
The same angle of prism should be used for all the
observations.
SOURCES OF ERRORS
Pin pricks may be thick.
Measurement of angles may be wrong.
CONCLUSION
From our investigation, it’s clear that the angle of deviation depends
significantly on the angle of incidence when using a hollow prism
filled with various transparent fluids. Notably, the deviation
decreases with increasing incidence angle until a minimum deviation
is reached, then it starts to increase. This relationship varies with the
fluid's refractive index inside the prism, showing higher deviations
for fluids with higher refractive indices. Understanding this interplay
is crucial in applications involving prisms in optics, like in
spectroscopy and refractometry.
BIBLIOGRAPHY
The following sources were used for the appropriate information
required to complete the project:
1. Comprehensive: Practical Physics Class XIl
2. NCERT textbook of class XII
3. Google
