PM SHRI JAWAHAR NAVODAYA
VIDYALAYA KHEDA, GUJARAT
PHYSICS INVESTIGATORY
PROJECT
AISSCE 2023-24
AIM: REFRACTION OF LIGHT BY-
AMAN YADAV
CLASS:12TH
A
ROLL NO :
02
CERTIFICATE
THIS IS CERTIFY THAT AMAN ,A
STUDENT OF CLASS XII-A, ROLL NO 02
HAS SUCCESSFULLY COMPLETED THE
RESEARCH ON THE BELOW MENTIOND
PROJECT UNDER MY GUIDANCE
DURING THE SESSION 2023-24,IN
PARTIAL FULFILLMENTOF PHYSICS
PRACTICAL EXAMINATION CONDUCT
BY CBSE IN PM SHRI JAWAHAR
NAVODAYDA VIDYALAYA
KHEDA,GUJRAT.
STUDENT SIGN TEACHER
SIGN
ACKNOWLEDGEMENT
IN THE ACCOMPLISHMENT OF THIS PROJECT
SUCCESSFULLY, MANY PEOPLE HAVE BEST OWNED
UPON ME THEIR BLESSING AND THE HEART PLEDGE
SUPPORT, THIS TIME IAM UTILIZING TO THANK ALL
THE PEOPLE WHO HAVE BEEN CONCERNED WITH
PROJECT
PRIMARILY I WOULD THANK HOD FOR BEING ABLE
TO COMLETE THIS PROJECT WITH SUCCESS. THEN I
WOULD LIKE TO THANK MY PHYSICS TEACHER
MAST. ,WHOSE VALUABLE GAUIDANCE HAS BEEN
THE ONES THAT HELPED ME PATCH THIS PROJECT
AND MAKE IT FULL PROOF SUCCESS HIS
SUGGETIONS AND HIS INSTRUCTION HAS SRVED AS
THE MAJOR CONTRIBUTOR TOWARD THE
CONPLTION OF THE PROJECT
THAN I WOULD LIKE TO THANK MY PARENT AND
FRIENDS WHO HAVE HELPED ME WITH THEIR
VALUABLE SUGGESTIONS AND GUIDANCE HAS
BEEN HELPFUL IN VARIOUS PHASES OF THE
COMPLTION OF THE PROJECT
CONTENT
1.CIRTIFICATE
2.ACKNOWLEDGEMENT
3.INTRODUCTION
4.EXPERIMENT
Introduction
This project envisages the use of hollow glass prism to
calculate the refractive indices of various liquids. The
hollow glass prism is filled with the liquid and then the
deviation in the path of the ray of light, as it suffers
refraction, is studied. Readings of the experiment are noted
with the various liquids and refractive index is calculated
for each pair of media.It has been assumed that the
refractive index of the liquids is with respect to that of
air.Important general terms related to refraction of light
are given below:-
Refraction:
In a homogenous medium, light travels along a straight line.
But whenever it falls on the surface of another medium, a
very small fraction of it is reflected back and most of the
light passesinto the medium, though with a change of
direction. This phenomenon of the bending of light asurface
of separation of two media is called refraction of light.
Cause of Refraction:
The phenomenon of refraction takes place when a beam of
light enters a medium in which light travels with a different
velocity.
Laws Of Reflection:
1. The reflected ray, the incident ray, and the normal at
the point of incidence all lie in the same plane.
2. The angle of incidence is equal to the angle of
reflection.
Laws Of Refraction:
1. The incident ray, the refracted ray, and the normal at
the point of incidence all lie in the same plane.
2.For any two given media the ratio sin i / sin r is a constant
(where i is the angle of incidence, r is the angle of
refraction). This is also called Snell's Law.
Refractive Index:
Refractive Index:
For a monochromatic light, the ratio of the sine of
the angle of incidence to the angle of refraction is a
constant for two given media in contact.If "i" is the
angle of incidence and "r" the angle of refraction then
sin i / sin r = constant.
This constant is called the refractive index. For most
purposes it may be assumed that the refractive index is
w.r.t. air. When light travels from rarer to denser medium
it bends
towards the normal and when it travels from denser to
rarer medium it bends away from the normal. It has been
experimentally determined that refractive index of a
substance,
µ= c/v.
c=the speed of light in vacuum
v= the speed of light in the substance
Prism:
A portion of transparent medium bounded by two
plane surfaces inclined to each other at a suitable angle is
called a prism. The angle between the two faces is known
as the angle of the angle of the prism or the refracting
angle.
Refractive Edge:
The line of interaction of the edges of the planes is known
as the refractive edge of the prism.
Angle of Deviation:
The angle through which the incident ray of light is deviated
is called the angle of deviation. It is the angle
between the emergent
ray and the incident ray produced.
Angle of Minimum Deviation:
As the value of the angle of incidence (i) increases, the angle
of deviation (d) decreases till for a particular value of angle
of incidence, it attains a minimum value 'Dm' called
The angle of minimum deviation and then increases again. At
this angle (Dm) the incident ray and the emergent ray are
symmetrical w.r.t. the refracting surfaces.
Critical Angle:
It is that angle of incidence in the denser medium for
which the corresponding angle of refraction in the rarer
medium is 90 degrees.
µ = l/sin c where
µ = Refractive Index
c= critical angle
Relation between refractive index and critical angle
b
according to Snell's Law: µa= sin i/ sin r where i = c
and r = 90°
b
µa = sin c/ sin 90° = sin c
b a
But µa = 1/ µb
a
i.e. 1/ µb = sin
a
c or µb= 1/sin
c
PRISM FORMULA
Let ABC represent a section of the glass prism and let L be
a ray incident at an angle "I" on the first face AB of the
prism
’
at a point "E". NN is the normal to this face.
The material of the prism is denser with respect to air, as
such the ray would refract in the direction EF making an
angle r with the normal, reaching the second face AC of
the
’
prism at the point F making an angle e with the normal MM .
The ray emerges in the
direction FS bending away from the normal making an angle
"e" with the normal.
If the incident ray PE be produced forwards to meet FS (also
to be produced backwards) at G then the angle HGF is called
the angle of deviation and is represented by D. Angle "BAC" is
called the refracting angle of the prism and represented by
"A".
From the figure it can be proved:
D = (I + e) - (r1 + r2) (using exterior angle property of
a triangle)
and A = (r1 + r2)
Therefore A + D = I + e; when angle of deviation D has the
minimum value Dm, the following conditions are fulfilled
I = e and r1 = r2 = r (say)
Applying these conditions in the equation
A = 2r Or r = A/2 A + Dm = 2I
I = (A + Dm)/2
1
Since µ2 = sin i/ sin r
1
µ = {sin(A + Dm)/2}/{sin A/2}
Experiment
AIM:
To find out the refractive indices of different liquids using a
hollow prism and to find the speed of light in given
transparent fluids.
APPARATUS:
• Hollow glass prism
• Drawing board
• Pins
• Meter scale
• Protractor
• Sheets of white paper
• Various liquids
a) Glycerine
b) Water
c) Vinegar
d) Vegetable Oil
THEORY:
Light is an electromagnetic radiation that is visible to the
human eye usually having a wavelength in the range of 400
nm to 700 nm between the infrared, with longer
wavelengths and the ultraviolet with the shorter
wavelength. The speed of light in vacuum is found to be
exactly 299,792,458 m/s. Observable events that result
from the interaction of light and matter are called optical
phenomenon. Refraction is a surface phenomenon due to a
change in its transmission medium.
When a ray of light passes from one medium into the other, it
either bends towards the normal or away from the normal in
the second medium. This phenomenon is known as the
refraction of light.
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.
For a particular pair of two media and for a particular
wavelength of light (colour) the ratio of the sine of the angle
of incidence and the sine of the angle of refraction is a
constant quantity called the refractive index of the
2
second medium w.r.t. the first. It is represented by ------ µ1
= sin i / sin r.The value of the angle of incidence "i" can be
obtained in the terms of the refracting angle "A" of the prism
and the angle of minimum deviation "Dm" and the angle of
refraction "R" can also be obtained in terms of the refracting
angle "A" of the prism. Thus we find that we can use the
above relation derived for determining the refractive index.
The experiment thus consists in finding the value of the
refracting angle "A" of the prism and the value of the angle of
minimum deviation Dm.
The refractive index of the liquid
Is given by the formula:
µ = {sin(A + Dm)/2}/{sin A/2}
For finding the value of Dm a curve is plotted between
angles of incidence (i) and their respective angles of
deviations (d).
PROCEDURE
A) For finding the angle of prism
• Take a piece of white paper, fix it on a drawing
board using board pins.
• Place the hollow glass prism on the sheet and carefully
draw its outline. Draw a normal and carefully draw its
outline.
• Draw a normal and an incident ray at an angle of 35
degrees with the normal on side AB of the prism.
• Fix two pins P1 and P2 on the incident ray which are at
least 5 cm apart.
• Fill the prism with water and place it over its outline.
Observe the refracted ray that comes after refraction
from the face AB
of the prism.
• Fix two more pins P3 and P4 to cover the image of P1 and
P 2.
• Obtained angles r1 and r2 and add them to obtain the
angle of the prism.
B) For finding the angle of minimum deviation
Fix a white sheet of paper on a drawing board using board
pins
• Place a hollow glass prism on the sheet and carefully
draw its outline. Draw a normal and an incident ray of
angle of incidence 35 degrees on the side AB of the
prism.
• Fix two pins P1 and P2 on the incident ray at least 5 cm
apart.
• Fill the hollow prism with water and place it over its
drawn outline. Observe the refracted ray which comes
after
refraction by placing two more pins P3 and P4 covering P1 and
P 2.
• Extended the incident and refracted ray to obtain the
angle of deviation, D.
• Repeat the above procedure taking other liquids and the
angles of incidence as 40° , 45° , 50° , 55° and 60°. Note
the lowest obtained value of angle of deviation as the
angle of minimum deviation, Dm .
• Using the value of the angle of prism (A) and the angle
of minimum deviation (Dm), calculate the value of the
refractive index of the liquids by using the equation
given in the theory.
Select suitable scales to represent the angle of incidence
along the X-axis and angle of deviation along
• the Y-axis and plot a graph. The graph gives the value of
•
• Dm, which is the minimum most point of the parabola.
•
S.No. Angle of Angle of
Name of Liquid
Incidence Deviation
1 35° 25°
2 40° 24°
3 45° 23°
Water
4 50° 25°
5 55° 27°
6 60° 28°
7 35° 26°
8 40° 25°
9 45° 23.5°
Vinegar
10 50° 25°
11 55° 27°
12 60° 28°
13 30° 49°
14 35° 40°
15 40° 39°
Vegetable Oil
16 45° 34°
17 50° 36°
18 55° 39°
19 35° 41°
20 40° 38°
21 45° 36°
Glycerine
22 50° 35°
23 55° 36°
24 60° 38°
CALCULATIONS:
A) Refractive index of liquids
Angle of prism (A) = 60°
Formula used: µ= {sin ((A + Dm)/2}/{sin (A/2)}
Water:
Dm=23
sin 41.5 0.6626
= =1.3252
Therefore µ = sin 30 0.5
Vinegar:
Dm=23.5°
sin 41.25 0.6593
=1.
Therefore µ = sin 30 0.5
3186
=
Vegetable Oil:
Dm=34°
sin 47.0 0.7314
= =1.4628
Therefore µ = sin 30 0.5
Glycerine:
Dm=35°
sin 47.5 0.7373
= =1.4746
Therefore µ =sin 30 0.5
Sl Speed of light v= Speed of
Liquid C light
no N (m/s)
(m/s)
8 8
1 Water 3×10 /1.3252 2.26×10
8 8
2 Vinegar 3×10 /1.3186 2.27×10
8 8
3 Vegetable oil 3×10 /1.4626 2.05×10
8 8
4 Glycerine 3×10 /1.4726 2.03×10
B) Speed of light in liquids
Graph for angle of minimum deviation
RESULT
The refractive indexes of the four liquids were found to be as
follows:-
• Water, µ = 1.3252
• Vinegar, µ = 1.3186
• Vegetable Oil, µ = 1.4628
• Glycerine, µ = 1.4726
The speeds of light in the four liquids were found to be as
follows:-
8
• Water, v=2.26×10 m/s
8
• Vinegar, v=2.27×10 m/s
8
• Vegetable oil, v=2.05×10 m/s
8
• Glycerine, v=2.03×10 m/s
THANK YOU
