PHYSICS
INVESTIGATORY
PROJECT
ACKNOWLEDGEMENT
I would like to express my sincere thanks to
my exceptional learned mentor, Mrs Julie who
inspired me to carry out the project. Her
guidance enabled me to think logically and
produce good results. I am also thankful to my
affectionate laboratory technician for her cooperation and help without which I would not
have completed my experiment successfully.
BONAFIDE CERTIFICATE
THIS IS TO CERTIFY THAT THIS BONAFIDE RECORD HAS
BEEN DONE BY ROLL NO .----------- IN THE SCHOOL
LABORATORY DURING THE YEAR
2014-2015.
INDEX
AIM
INTRODUCTION
REQUIREMENTS
PROCEDURE
OBSERVATION
CALCULATIONS
RESULT
PRECAUTIONS AND SOURCES
OF ERROR
AIM....
TO INVESTIGATE THE DEPENDENCE OF
THE ANGLE OF DEVIATION, ON THE
ANGLE OF INCIDENCE , USING
HOLLOW PRISM FILLED WITH
DIFFERENT TRANSPARENT FLUIDS.
INTRODUCTION
 REFRACTION: THE PHENOMENON OF BENDING OF
LIGHT FROM ITS STRAIGHT LINE PATH ON THE
SURFACE OF SEPERATION OF TWO OPTICAL MEDIA IS
KNOWN AS REFRACTION OF LIGHT.
 LAW OF REFRACTION ( SNELLS LAW) : THE RATIO OF
THE SINE OF THE ANGLE OF INCIDENCE TO THE SINE
OF ANGLE OF REFRACTION IS CONSTANT FOR A GIVEN
PAIR OF MEDIA AND FOR A GIVEN COLOUR OF LIGHT.
SYMBOLICALLY,
( µ= REFRACTIVE INDEX)
 REFRACTIVE INDEX : REFRACTIVE INDEX OF A
MEDIUM FOR A GIVEN WAVELENGTH OF LIGHT IS
DEFINED AS:
µ=
 ANGLE OF INCIDENCE : THE ANGLE BETWEEN THE
INCIDENT RAY AND THE NORMAL RAY.
 ANGLE OF DEVIATION : THE ANGLE BETWEEN THE
INCIDENT RAY AND THE EMERGENT RAY IS CALLED THE
ANGLE OF DEVIATION DENOTED BY LETTER “D” OR “ δ “.
 MINIMUM DEVIATION: WHEN A PRISM IS SO PLACED
WITH RESPECT TO THE INCIDENT RAY THAT THE ANGLE
OF DEVIATION PRODUCED BY IT IS MINIMUM, THEN THE
PRISM IS SAID TO BE IN THE POSITION OF MINIMUM
DEVIATION.
 DISPERSION: THE PHENOMENON OF SEPERATION OF
WHITE LIGHT INTO ITS COMPONENT COLORS DUE TO
VARIATION IN VELOCITIES OF DIFFERENT COLORS
WHILE PASSING THROUGH THE PRISM IS CALLED
DISPERSION OF LIGHT.
REQUIREMENTS










DRAWING SHEET
DRAWING BOARD
PINS
PENCIL
HOLLOW GLASS PRISMS
GLYCERINE
VINEGAR
WATER
PROTRACTOR
RULER
PROCEDURE
 FIX THE SHEET OF WHITE PAPER ON THE DRAWING BOARD
WITH DRAWING PINS.
 PLACE THE PRISM FILLED WITH LIQUID ON THE PAPER
AND TRACE ITS BOUNDARY “ABC”.
 MARK A POINT “O” ON ONE OF THE REFRACTING SURFACES
AND DRAW A NORMAL TO THE SURFACE AT THIS POINT.
 DRAW A STRAIGHT LINE “PQ” CORRESPONDING TO
INCIDENT RAY DRAWN AT A SUITABLE ANGLE WITH THE
NORMAL.
 FIX TWO PINS “P” AND “Q” ABOUT 5CM APART ON THE
INCIDENT RAY LINE AN VIEW ITS IMAGE WITH ONE EYE
CLOSED FROM THE SIDE “AC” OF THE PRISM. FIX TWO
PINS “R” AND “S” SUCH THAT THE TIPS OF THESE PINS
AND THE TIPS OF THE IMAGES OF THE INCIDENT RAY
PINS “P” , “Q” LIE IN THE SAME STRAIGHT LINE.
 ENCIRCLE THE PIN PRICKS ON THE PAPER. REMOVE THE
PINS “P” , “Q” AND ALSO ENCIRCLE THEIR PIN PRICKS.
 JOIN POINTS “S” AND “R” AND PRODUCE IT BACKWARDS
TO MEET THE INCIDENT RAY “PQ” PRODUCED. THUS, “RS”
IS THE EMERGENT RAY CORRESPONDING TO THE
INCIDENT RAY “PQ”. DRAW ARROW HEADS TO SHOW THE
DIRECTION OF THE RAYS.
 MEASURE THE ANGLE OF DEVIATION “δ” WITH A
PROTRACTOR AND MEASURE PRISM ANGLE.
OBSERVATIONS
GLYCERINE
S.NO
ANGLE OF
INCIDENCE
ANGLE OF
DEVIATION
01.
30°
45°
02.
40°
38°
03.
50°
40°
04.
60°
48°
 VINEGAR
S.NO
ANGLE OF
ANGLE OF
INCIDENCE
DEVIATION
01.
30°
20°
02.
40°
25°
03.
50°
28°
04.
60°
30°
 WATER
S.NO
ANGLE OF
INCIDENCE
ANGLE OF
DEVIATION
01.
30°
24°
02.
40°
23°
03.
50°
20°
04.
60°
27°
CALCULATIONS
 GLYCERINE:
=

VINEGAR:
=

WATER
RESULT
THE ANGLE OF DEVIATION FIRST DECREASES
WITH INCREASE IN ANGLE OF INCIDENCE
ATTAINS A MINIMUM VALUE AND THEN
INCREASES WITH FURTHER INCREASE IN
ANGLE OF INCIDENCE.
PRECAUTIONS AND SOURCES OF
ERROR
 A SHARP PENCIL SHOULD BE USED.
 PROPER ARROWS SHOULD BE DRAWN TO
INDICATE THE INCIDENT, THE REFRACTED AND
THE EMERGENT RAY.
 A SMOOTH CURVE PASSING THROUGH ALL THE
POINT SHOULD BE DRAWN.
 THE ANGLE OF PRISM SHOULD BE USED FOR ALL
OBSERVATIONS.
 PINS SHOULD HAVE SHARP TIPS AND BE FIXED
VERTICALLY.
 VISIBILITY OF PINS MAY BE LOW FOR COLOURED
LIQUIDS, THEY MAY BE ILLUMINATED BY A
SOURCE OF WHITE LIGHT.
BIBLIOGRAPHY
 WIKIPEDIA
 LAB MANNUAL CLASS XII
 www.google.com