KENDRIYA VIDYALAYA No. 2,
Pondicherry University Campus, Kalapet, Puducherry-14
PHYSICS INVESTIGATORY PROJECT
2013-‘14
DETERMINATION OF REFRACTIVE INDICES OF
VARIOUS LIQUIDS USING A HOLLOW PRISM
Guided by,
Submitted by,
Class XII
BONA FIDE CERTIFICATE
It is hereby to certify that, the original and genuine investigation
work has been carried out to investigate about the subject matter
and the related data collection and investigation has been
completed solely, sincerely and satisfactorily done by
NAME of Class XII, Kendriya Vidyalaya No.2, Pondicherry-14,
regarding the project titled, “REFRACTIVE INDICES OF
VARIOUS MEDIUMS”
Signature of the Guide
Principal’s Signature
Submitted for ALL India SENIOR SECONDARY
EXAMINATION held on _____________ at KENDRIYA
VIDYALAYA No.2, PONDICHERRY.
Internal Examiner
External Examiner
ACKNOWLEDGEMENT
The successful completion of any task would be
incomplete without mentioning the names of those persons who
helped to make it possible. I take this opportunity to express my
gratitude in few words and respect to all those who helped me in
the completion of this project.
It is my humble pleasure to acknowledge my deep senses of
gratitude to my Physics teacher, Teacher name for her valuable
support, constant help and guidance at each and every stage,
without which this project would not have come forth.
I also register my sense of gratitude to our principal,
Mr.principal, for his immense encouragement that has made
this project successful.
I would also like to thank my friends and family for encouraging
me during the course of this project.
Last, but not the least, I would like to thank CBSE for giving us
the opportunity to undertake this project.
Project Overview
Aim
Apparatus Required
Theory
Procedure
Observations
Conclusions
Precautions
Bibliography
Aim
To find out the refractive indices of different liquids using a
hollow prism
Apparatus Required
 Hollow glass prism
 Various liquids like water, carbon disulphide, benzaldehyde
etc.
 Bell pins
 Drawing board
Theory
A 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
Procedure
 Fix a white sheet of paper on the drawing board with help
of drawing pins.
 Keep the prism and mark the outline of it as ABC.
 Drop a normal PQ on the side AB.
 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.
 Place the prism filled with given sample of liquid ,on the
marked outline ABC.
 Now take the pins and place them on the side AC so that all
the 4 pins appear to be in same line.
 Remove the prism and draw the line joining the points so
obtained.
 Mark the diagram as shown in the figure.
 Repeat this with different liquids and different angle of
incidence.
Observation
 Benzaldehyde
S.no
a º(angle of prism) i º (angle of incidence) d º (angle of deviation)
1
2
3
4
5
60
60
60
60
60
30
35
37.5
39
40
45
42
40
42
45
U=sin((60+40)/2)/sin(30)
= 1.504
 Water
S.no
a º(angle of prism) i º (angle of incidence) d º (angle of deviation)
1
2
3
4
5
6
60
60
60
60
60
60
30
35
40
45
50
55
U=sin((60+22)/2)/sin(30)
= 1.306
25
22
20
22
25
28
 Dil. Sulphuric Acid
S.no
a º(angle of prism) i º (angle of incidence) d º (angle of deviation)
1
2
3
4
5
60
60
60
60
60
20
30
35
40
45
U=sin((60+25)/2)/sin(30)
= 1.351
33
30
25
29
30
Conclusion
Refractive indices at room temperature:
 Benzaldehyde
o Actual:
1.546
o Experimental: 1.504
o
 Water
o Actual:
1.33
o Experimental: 1.306
o
 Dil . Sulphuric acid
o Actual:
1.355
o Experimental: 1.351
Precautions
 Angle of incidence should lie b/w 35-60 degree.
 Pins should be vertically fixed and should lie in same line.
 Distance b/w two points should not be less than 10mm.
 Same angle of prism should be used for all observation.
 Arrow head should be marked to represent emergent and
incident ray.