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 co-operation 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 INCIDENCE

ANGLE OF 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