PHYSICS PROJECT
NAME – MD ZAID
CLASS – XII
SECTION – B
SESSION – 2024-25
BOARD ROLL NO – ____________
SCHOOL – ABHINAV BHARATI HIGH
SCHOOL, KOLKATA
SUBJECT – PHYSICS (042)
TOPIC – DETERMINATION OF REFRACTIVE
INDEX OFLIQUIDS USING HOLLOW PRISM
ACKNOWLEDGEMENT
I would like to convey my heartfelt
gratitude to my physics teacher
Mr Sukanta for his tremendous
support and assistance in the
completion of my project. I would also
like to thank our Principal, Mrs
Sraboni Samanta for providing me
with this wonderful opportunity to
work on the project. The completion of
the project would not have been
possible without their help and
insights.
-MD ZAID
XII B
CERTIFICATE
This is to certify that Md.Zaid
Board Roll No.________ of class XII-B of
Abhinav Bharati High School, Kolkata has
successfully completed his project for
Physics (042) for the partial fulfilment of
AISSCE, as prescribed by the CBSE for the
session 2024-25.
Signature of the External Examiner:
Signature of the Principal:
Signature of the Subject Teacher:
INDEX
PAGE
S.NO NO SIGNATURE
CONTENT
1. AIM 5
2. APPARATUS 5
REQUIRED
3. THEORY 6-9
4. PROCEDURE 10
5. OBSERVATION 11
6. CALCULATION 11
7. PRECAUTIONS 12
8. SOURCE OF ERROR 12
9. REFERENCE 12
AIM: To investigate the dependance of
the angle of deviation' on the angle of
incidence using a hollow prism filled, one-
by-one, with different transparent fluids.
APPARATUS REQUIRED:
o Drawing board
o White sheets of paper
o Hollow prism
o Different liquids (water, sprite, glycerine)
o Half metre scale,
o Thump pins,
o Graph papers
o Pencil
o Protractor
THEORY
Prism is a transparent optical element with flat,
polished surfaces that refract light. Prisms can
be made from any material that is transparent
including glass, plastic and fluorite. A prism
can be used to break light up into its
constituent spectral colors. Prisms can also be
used to reflect light, or to split light into
components with different polarizations. The
refractive index of the liquid Is given by the
formula:
U=sini/sinr=sin((a+d)/2)/sin(a/2)
Where, U=refractive index of the liquid;
a= the angle of minimum deviation;
d=angle of prism;
i=angle of incidence;
r=angle of refraction;
Refraction of light through a prism-
Diagram shows section ABC of a prism taken
by a vertical plane, perpendicular to the
edge. BC is the base of the prism and AB and
AC are its two refracting surfaces.
RQ is the incident ray.
QS is the refracted ray.
ST is the emergent ray.
∠RQN1 = i = angle of incidence
∠SQN3=r1=angle of refraction inside prism
∠QSN3=r2=angle of incidence inside prism
∠TSN2=e=angle of emergence
∠BAC=A=angle of prism
∠SFK=D=angle of deviation
In △QFS, ∠KFS=∠FQS + ∠FSQ
D= (1-r1) + (e-r2)
D=1+e-(r1+r2) ….(1)
In △QS1N3, r1+r2+∠QN3S=180°....(2)
The quadrilateral AQN3S is cyclic quadrilateral,
then A+∠QN3S=180° …(3)
From (2) and (3)
A=r1 +r2
Eq. (1) becomes,
D=i+e-A
D+A=i+e
Angle of Minimum Deviation-
(a) Definition. The minimum value of angle of
deviation, is called angle of minimum deviation. It is
represented by the symbol D
(b) Explanation. For same angle of deviation (D)
there are two values of angle of incidence. One
value equals i and other value equals 'e'.
As angle i is increased from a small value, e
decreases from large value and angle of deviation
decreases. When angle of deviation is minimum
(Dm), then, i and e become equal. The
refracted ray QS goes parallel to base BC.
Since i = e, we have r1 =r2 {∵n= sini/sinr1=sine/sinr2}
Hence, at minimum deviation, when r1=r2 =r (say),
we have, A=r1+r2=r+r=2r or r=A/2
Also, at minimum deviation, D=Dm and i=e
From relation, A+D=i+e
we have, A+Dm=i+i=2i or i=A+Dm/2
From Snell's law, n= sini/sinr
we have, n= sinA+Dm/2/sinA/2
This relation is useful for determination of n
for prism material.
DIAGRAM
PROCEDURE
o Fix a white sheet of paper on the
drawing board with help of drawing
pins.
o Keep the prism and mark the outline of it
as ABC.
o Drop a normal PQ on the side AB.
o Draw the angle of incidence in
accordance with the normal PQ and
place 2 pins so that they appear to be
in the straight line.
o Place the prism filled with given sample
of liquid, on the marked outline ABC.
o Now take the pins and place them on
the side AC so that all the 4 pins appear
to be in same line.
o Remove the prism and draw the line
joining the points obtained.
o Mark the diagram as shown in the
figure.
o Repeat this with different angle of
incidence
OBSERVATION:
Angle of hollow prism A= 60°
Angle of Angle of Angle of
S.NO Angle of Deviation Deviation Deviation
Incidence for water for sprite for glycerine
1. 35° 26° 26° 37°
2. 45° 22° 24° 34°
3. 55° 20° 22° 32°
4. 60° 22° 25° 35°
5. 65° 26° 28° 39°
CALCULATION:
Plot the graphs between angle of incidence (∠i)
and angle of deviation (∠D) by taking i along X-axis
and ∠D along Y-axis for each transparent liquid.
From the graph find the value of angle of minimum
deviation Dm corresponding to the lowest point of
the graphs. Let the value of angle of
minimum deviation. Dm=
PRECAUTIONS
1.The pins should be fixed vertical.
2. The distance between the two pins should
not be less than 10 mm.
3. Arrow heads should be marked to
represent the incident and emergent rays.
4. The same angle of prism should be used for
all the observations.
SOURCES OF ERRORS
1. Pin pricks may be thick.
2. Measurement of angles may be wrong.
REFERENCE
• DINESH LAB MANUAL
• www.googleimage.com
• www.wikipidea.com
