Comparative Study of the Concentration Dependence ofDifferent Softdrinks Using Refractive Index

____________________________

A Research Presented to the Faculty of

Holy Trinity College, Puerto Princesa City

______________________________

In Partial Fulfillment of the Requirements

For the Subject Physics I

______________________________

By:

Abadilla, Abraham F.

Canon, Gaea A.

Cuadra, Cristy Marie O.

Faigao, Anna Margarita O.

Magay, Mary Stephanie T.

Mestidio, Teresa P.

Omiple, Kathlyn Rose R.

Pacanza, Andrea E.

Holy Trinity College

January 2010

Approval Sheet

The research study entitled “Comparative Study of the Concentration

Dependence of Different Softdrinks Using Refractive Index”, prepared and submitted by

Cristy Marie Cuadra, et al., in partial fulfillment for the requirements for the subject

Research I has been examined for oral examination.

__________________

Mrs. Geraldine Failon

Adviser

Panel of Examiners

Approved by the Committee on Pre-oral Examination with the grade of _____%.

__________________

Chairman

_____________ ____________

Member Member

Accepted and approved in partial fulfillment of the requirements for the subject

Physics I.

____________________

Sr. Pinlyn Dahili, O.P.

Principal

Date: __________________

ii

Acknowledgement

The researchers would like to express their sincere appreciation and deep

gratitude to the following that have been of great help for the completion of this

investigatory project:

Mrs. Geraldine Failon, our Physics teacher, for her patience and unending words of

support that encouraged the researchers to pursue the studies:

To their beloved principal, Sr. Pinlyn Dahili, O.P., for giving the researchers a chance to

conduct this research study;

To Ms. Lany Omilda, Basic Education Department Laboratory-in-Charge, for allowing

the researchers to use the College Laboratory for our Investigatory Project;

To their co-researchers, for their enthusiasm in their study;

To their classmates, friends and teachers, for their moral support;

To their beloved parents, for their moral and financial support and words of

encouragement;

And most of all, to our Almighty Father, for giving us strength and perseverance and for

making this research study possible.

The Researchers

iii

Dedication

This research study is wholeheartedly and sincerely

dedicated to our parents, teachers, friends, classmates,

loved ones, brothers and sisters and to our dear Alma Mater.

- The Researchers

iv

TABLE OF CONTENTS

Page

Title Page - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - i

Approval Sheet - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - ii

Acknowledgement - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - iii

Dedication - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - iv

Abstract - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - vi

CHAPTER I – THE PROBLEM AND ITS BACKGROUND

Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1

Statement of the Problem - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - -- - - - - 2

Significance of the Study - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2

Scope and Limitation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - -3

Research Paradigm - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- -- - 3

Definition of Terms - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -4

CHAPTER II - REVIEW OF RELATED LITERATURE

Local Literature - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - -- - - - -5

Foreign Literature - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - 6

Local Study - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7

Foreign Study - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -8

Synthesis - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -9

v

CHAPTER III – RESEARCH METHODOLOGY

Research Design - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10

Materials and Instrumentation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - 10

Experimental Procedure - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - -- - 11

Making the Prism from Microscope Slides - - - - - - - - - - - - - - - - - - - - - - - - 11

Measuring the Index of Refraction of a Liquid - - - - - - - - - - - - - - -- - - - - - - 13

CHAPTER IV – RESULTS AND DISCUSSION

Presentation of Data - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17

Interpretation of Data - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --- 18

Discussion - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 18

CHAPTER V – SUMMARY, CONCLUSION, AND RECOMMENDATION

Summary - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 19

Conclusion - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20

Recommendation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20

BIBLIOGRAPHY - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21

APPENDIX - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- -23

vi

ABSTRACT

This research study entitled, “Comparative Study on the Concentration

Dependence of Different Softdrinks Using Refractive Index” aimed to see if sugar

concentrations in different softdrinks can be determined using the dependence of

refractive index on the concentration by laser-based measurement.

The materials used were bought from different shops in Puerto Princesa City and

were eventually collected. The experimental part was divided into two parts: the Making

of the Prism from Microscope Slides, and Measuring the Index of Refraction of a Liquid.

The first of part of the experimental procedure, the Making of the Prism from

Microscope Slides, was performed at one of the researcher’s house. The said

microscope slides were constructed to create a hollow glass prism, which would be

used on the second part of the procedure.

The second part of the experimental procedure, the Measuring of the Index of

Refraction of a Liquid, was performed the following day at College Department Physics

Laboratory, Holy Trinity College. In the experiment, a low-power laser pointer with an

output of 1mW and a wavelength of 630 to 680nm was used as a light source.

The beam was pointed at the prism filled only with air (has no liquid inside) and

this resulted the beam to hit straight on the wall. Refraction occurs when the laser beam

was pointed on the glass prism filled with liquid. The beam went on some distance away

from its original position (the first measurement, prism filled with air) when the prism is

filled with water. Likewise, the beam changed its position when it was filled with Classic

Coca-Cola, Classic Pepsi-Cola, Diet Coca-Cola, and Diet Pepsi-Cola. The different

variants yielded different points on the wall, as compared to the points where the

undiverted and the water-filled beam resulted.

Results showed that Coca-Cola Classic had 1.36RI, the highest refractive index

amount; 3.38 g of sugar concentration, 39.4 cm for X and 84.2 cm for L measurements;

and 25.2 for the minimum deviation (qmd). Other experimental variables had a lesser

value as compared to Coca-Cola Classic, as well as the control variable (water and air-

filled prism). The researchers therefore conclude that Coca-Cola Classic had the

highest amount of sugar concentration.

The researchers further recommend on using Laser-based Refractive Index

Method to find the concentration and the refractive index of liquids. The researchers

also recommend on using this procedure to find the RI of salt and sugar solutions,

sodas, and other beverages.

vii

CHAPTER I

The Problem and Its Background

Introduction

Laser-based measurements have been found in early 1900 indirectly by Albert

Einstein during the research of photoelectric effects and until now, its application still

growth. One of its applications is in measuring the concentration of a solution, such as

sugar concentrations.

Softdrinks are known to have large concentrations of sugar. Regular or Classic

softdrinks had the common measurement, while diet softdrinks had a lesser amount as

compared to the regular ones. High concentrations of sugar in softdrinks were alleged

as one of the reasons of diseases in humans, and are highly acidic.

Snell's Law describes the physics of refraction. If we follow a light ray as it

passes from air to water, we can see how the light bends. Air and water each have a

different index of refraction. Snell's Law describes the angle of refraction of a light ray in

terms of the angle of incidence and the index of refraction of each of the materials

through which the light is passing.

However, what Snell's Law tells us is that the greater the relative index of

refraction, the more the light bends. The index of refraction of a liquid depends on the

density of the liquid. Hence, dissolving sugar in water results in a solution with a density

greater than that of water alone. Since sugar water is denser than plain water, sugar

water should have a higher index of refraction than plain water.

Hence, the researchers are inspired to conduct a research study dependence of

refractive index (RI) on the concentration by laser-based measurement, and to see if

sugar concentrations in softdrinks can be determined using refractive index.

1

Statement of the Problem

This study entitled “Comparative Study of the Concentration Dependence of

Different Softdrinks Using Refractive Index” aims to see if sugar concentrations in

different softdrinks can be determined using the dependence of refractive index on the

concentration by laser-based measurement.

Specifically, this study sought to answer the following questions:

1. Can one study the basic properties of refraction and its interaction with matter

by using a laser?

2. Which of the two had the greater sugar concentration? The lesser?

3. Which is the denser liquid?

Significance of the Study

This study is deemed important to the following:

1. School

This research study will be beneficial to the school since serve as a basis of

facts for laboratory purposes.

2. Consumers

This research study will be beneficial to consumers as they can observe the

differences between products and compare them.

3. Science Classes

This research study will help the science classes for it can be another source of

knowledge that will contribute to the science world.

4. Future Researchers

This study will be a great help to the future researchers because this study will

serve as their guide and a source of inspiration in conducting future research studies.

2

Scope and Delimitation

Problem:

This study focuses in determining and comparing the sugar concentrations of

classic and diet variants of Coca-Cola and Pepsi-Cola.

Locale:

The experimental part was done at Holy Trinity College, College Department

Physics Laboratory, Quezon St., Puerto Princesa City.

Time Frame:

This study was done on January 2010.

Research Paradigm

Regular andDiet Variants ofCoca-Cola and

Pepsi-Cola

Laser-basedMeasurement on the

Index of Refraction of theSolution

Refractive Index of theRegular and Diet

Variants of Coca- Colaand Pepsi-Cola

By using the Laser-based Measurement on the Refractive Index Method, we

have been able to conclude that Classic Coca-Cola possesses the highest sugar

concentration, while both the Diet variants of Coca-Cola and Pepsi had the least.

3

Definition of Terms

The following terms are defined operationally:

1. Refraction - is the change in direction of a wave due to a change in its speed.

2. Snell’s Law - law governing refraction angle; the law stating that for a light ray

passing between two media the ratio of the sines of the angle of incidence and the

angle of refraction is a constant

3. Index of Refraction- ratio of light speeds; the ratio of the speed of refracted light in a

vacuum or reference medium to its speed in the medium under examination.

4. Density- amount of a substance contained within a specific area. In physics, density

is the ratio of the mass of a substance to its volume, and it can be calculated by dividing

the mass by the volume. Density is often expressed in units such as grams per cubic

centimeter (g/cm3) or pounds per cubic foot (lb/ft3).

5. Prism - solid for dispersing light; a transparent polygonal solid object with flat faces

and a usually triangular cross section, used for separating white light into a spectrum of

colors.

4

CHAPTER II

Review of Related Literature

Local Literature

Snell’s Law

This important law, named after Dutch mathematician Willebrord Snell, states

that the product of the refractive index and the sine of the angle of incidence of a ray in

one medium is equal to the product of the refractive index and the sine of the angle of

refraction in a successive medium. Also, the incident ray, the refracted ray, and the

normal to the boundary at the point of incidence all lie in the same plane. Generally, the

refractive index of a denser transparent substance is higher than that of a less dense

material; that is, the velocity of light is lower in the denser substance. If a ray is incident

obliquely, then a ray entering a medium with a higher refractive index is bent toward the

normal, and a ray entering a medium of lower refractive index is deviated away from the

normal. Rays incident along the normal are reflected and refracted along the normal.

In making calculations, the optical path, which is defined as the product of the

distance a ray travels in a given medium and the refractive index of that medium, is the

important consideration. To an observer in a less dense medium such as air, an object

in a denser medium appears to lie closer to the boundary than is the actual case. A

common example is that of an object lying underwater observed from above water.

Oblique rays are chosen only for ease of illustration. (Pinoy Exchange, 2009)

5

Refraction

When a wave passes from one medium to another, the frequency remains the

same but the velocity and wavelength change. Refraction refers to the change in

direction and change in wavelength or velocity of the wave that occurs as the wave is

transmitted from one medium to another. (Silverio, 2007)

Foreign Literature

Refraction and Refractive Index

Refraction is the change in direction of a wave due to a change in its speed. This

is most commonly observed when a wave passes from one medium to another.

Refraction of light is the most commonly observed phenomenon, but any type of wave

can refract when it interacts with a medium, for example when sound waves pass from

one medium into another or when water waves move into water of a different depth.

Refraction is described by Snell's law, which states that the angle of incidence θ1 is

related to the angle of refraction θ2 by where v1 and v2 are the wave velocities in the

respective media, and n1 and n2 the refractive indices. In general, the incident wave is

partially refracted and partially reflected; the details of this behavior are described by the

Fresnel equations.

In optics, refraction occurs when light waves travel from a medium with a given

refractive index to a medium with another. At the boundary between the media, the

wave's phase velocity is altered, usually causing a change in direction. Its wavelength

increases or decreases but its frequency remains constant. For example, a light ray will

6

refract as it enters and leaves glass, assuming there is a change in refractive index. A

ray traveling along the normal (perpendicular to the boundary) will change speed, but

not direction. Refraction still occurs in this case. Understanding of this concept led to the

invention of lenses and the refracting telescope. Refraction can be seen when looking

into a bowl of water. Air has a refractive index of about 1.0003, and water has a

refractive index of about 1.33. If a person looks at a straight object, such as a pencil or

straw, which is placed at a slant, partially in the water, the object appears to bend at the

water's surface. This is due to the bending of light rays as they move from the water to

the air. Once the rays reach the eye, the eye traces them back as straight lines (lines of

sight). The lines of sight (shown as dashed lines) intersect at a higher position than

where the actual rays originated. This causes the pencil to appear higher and the water

to appear shallower than it really is. The depth that the water appears to be when

viewed from above is known as the apparent depth. This is an important consideration

for spearfishing from the surface because it will make the target fish appear to be in a

different place, and the fisher must aim lower to catch the fish. (Wikipedia, 2010)

Local Study

A study from a certain group of students from University of the Philippines (UP)

Diliman Campus reports their observation of laser-induced refractive index change for

homeotropically aligned nematic liquid crystal film of 10mm thickness. Diffraction rings

were observed when an intense Ar+ ion laser hits homeotropically aligned nematic

liquid crystal at normal incidence above a threshold 110 KW/cm2, which correspond to

the threshold of the Optical Freedericksz Transition (OFT). Above the threshold, as the

7

laser intensity was increased, the number of observed diffraction tings likewise

increased. The mechanism for optical molecular reorientation has a great dependence

on elastic restoring forces. By exploring the dependence of bend elastic constant, K33

with Freedericksz transition, the value of the K33 was calculated at 2.6 x 10-12 N. To

investigate the behavior of Dn as a function of intensity, an experiment was performed

for oblique laser incidence. It was shown that the refractive index change increased

linearly from values of 0.001to 0.18 at laser intensities ranging from 50 KW/cm2 to 200

KW/cm2 . The Kerr coefficient n2 was calculated for various laser incidence angles.

Foreign Study

The Laser Institute of America conducted a study entitled “Visualization of

Refraction and Attenuation of Near-Infrared Laser Beam due to Laser-induced Plume”

to obtain a fundamental knowledge of the interaction between a near-infrared laser

beam and an induced plume during welding.

The plume was characterized by spectroscopy, and the effect and mechanism of

the laser-induced plume on the refraction and/or attenuation were investigated by high-

speed video observation of the plume and the probe laser, and power meter

measurement of the fiber probe laser beam of 1090 nm wavelength which passed

horizontally through the plume formed during bead-on-plate welding of an 8-mm-thick

type 304 plate with a 1.5 kW yttrium-aluminum-garnet (YAG) laser beam. The plume

induced by YAG laser at the focus position grew about 20 mm toward the incident laser

beam and was identified to be non-ionized metallic vapor of 3600 K in average

temperature on the basis of the spectroscopic analyses. The high-speed observation

8

images and the power measuring results revealed that the rapid movement and the low

brightness of the probe laser beam, seen after the plume, were caused by refraction due

to density difference between the plume and its environment and Rayleigh scattering

due to ultrafine particles, respectively. The maximum refraction and attenuation were

1.2 mrad and 3%, which were much lower than the beam divergence and the same

levels as power variation in the incident YAG laser beam under argon (Ar) shielding gas,

respectively. Moreover, the YAG laser-induced plume hardly affected the reduction in

weld penetration under the defocused conditions since the penetration of type 304 weld

made without Ar shielding gas was deeper than that produced with Ar shielding gas

although the former plume was longer than the latter one. This reason was interpreted in

terms of the greater effect of surface tension-driven melt flows. Consequently, the

wavelengths of near-infrared laser beams were desirable for laser welding in the case of

the laser-induced plume of less than 20 mm height, owing to their weak optical

interaction to the plume.

Synthesis

The Local and Foreign Literature describe the Laser-based Refractive Index as

one of the easiest and most effective ways on measuring the concentrations of different

substances. It also posits that refraction occurs whenever a laser beam hits a hollow

glass prism.

Subsequently, the Local and Foreign Study proves that many objects do react to

refraction, and that it is one of the effective methods in obtaining results in some

Physics-related subjects.

9

CHAPTER III

Research Methodology

This chapter contains the Research Design, Materials, and Instrumentation and

the Procedure of the Study.

Research Design

This study used descriptive and experimental method in order to observe, record,

and control the condition and status of the phenomenon which already exists and may

exist.

Materials and Instrumentation

· several 1" × 3" glass microscope

slides

· diamond scribe or glass cutter,

· ruler

· electrical tape

· epoxy glue (either 5-minute or

30-minute epoxy),

· toothpicks,

· laser pointer

· cardboard

· tape

· tape measure

· paper

· pencil

· piece of string

· sugar

· water

· graduated cylinder

· gram scale

· calculator with trigonometric

functions (sine, arctangent)

· Different softdrinks ( Coca-Cola

and Pepsi-Cola Classic and Diet

Variants)

10

Experimental Procedure

Making the Prism from Microscope Slides

1. Figure 1, below, shows the sequence of steps to be followed to make a hollow

glass prism in the shape of an equilateral triangle (Edmiston, 1999). The prism

will hold a liquid as you measure the liquid's index of refraction.

Figure 1. Diagram of the sequence of steps for making a hollow glass prism (equilateral triangle)

from microscope slides. (Edmiston, 1999)

2. The goal is an equilateral prism that can hold liquid. It will be constructed from

microscope slides and epoxy.

3. Put a piece of black electrical tape across the face of the slide as shown above

(Figure 1a). The tape should hang over the edge.

4. Score the other side of the microscope slide with a diamond scribe or glass cutter

11

as shown (Figure 1a). Use a straightedge to guide the diamond scribe. The two

scribe lines should be one inch apart and perpendicular to the long edge of the

slide. Break the glass along the scribe lines. Hold the slide on either side of the

first scribe line and bend the glass toward the taped side. Bend just enough to

break the glass. Repeat for the second scribe line (Figure 1b).

5. Now bend the glass away from the tape, allowing the tape to stretch (Figure 1c).

Continue bending until the triangle closes.

6. Place the prism on a flat surface to align the bottom edges. Use the overhanging

tape to secure the prism in this configuration (Figure 1d).

7. Adjust the edges of each face so that they align correctly. At each apex of the

prism, the inside edges should be in contact along their entire vertical length.

8. Follow the manufacturer's instructions for mixing the epoxy cement (usually you

mix equal amounts from each of two tubes). Use a toothpick to apply epoxy to

the inside corners of the prism to glue the three faces together (Figure 1e). The

corners need to be water-tight, but keep the epoxy in the corners and away from

the faces of the prism. Keep the bottom surface flat and allow the epoxy to set.

9. When the epoxy in the corners has set firmly, mix up fresh epoxy and use a

toothpick to apply it to the bottom edge of the prism. Glue the prism to a second

microscope slide as shown (Figure 1f). The bottom edge needs to be water-tight,

but keep the epoxy away from the faces of the prism.

10. Allow the epoxy to set overnight, and then the prism will be ready for use.

12

Measuring the Index of Refraction of a Liquid

1. Figure 2, below, is a diagram of the setup to be used for measuring the index of

refraction of a liquid. (Note that the diagram is not to scale.)

Figure 2. Diagram of setup for measuring the index of refraction of a liquid using a laser pointer

and a hollow triangular prism (not to scale; based on the diagram in Nierer, 2002).

2. The laser pointer should be set up so that its beam (dotted red line in Figure 2) is

perpendicular to a nearby wall. You should attach a big piece of paper to the wall

for marking and measuring where the beam hits. The height of the laser pointer

should be adjusted so that it hits about half-way up the side of the prism. The

laser pointer should be fixed in place. Check periodically to make sure that the

beam is still hitting its original spot.

3. When the prism is empty (filled only with air), then placing it in the path should

not divert the beam. Mark the spot where the beam hits the wall when the prism

is empty. When the prism is filled with liquid, the laser beam will be refracted

13

within the prism (solid blue line). The emerging beam (solid red line) will hit the

wall some distance away from the original spot of the undiverted beam. You will

measure the distance, x, between these two points (see Figure 2).

4. Figure 3, below, is a more detailed view of the prism which illustrates how to

measure the angle of minimum deviation, θmd. It is needed to mark points a, b,

and c in order to measure the angle. Points a and b are easy, because they are

project on the wall. Marking point c is more difficult, because it is under the prism.

The next several steps describe how to mark point c.

Figure 3. Detail diagram showing how to measure the angle of minimum deviation (not to scale;

based on the diagram in Nierer, 2002).

5. Tape a sheet of paper to the table, centered underneath the prism.

6. With the prism empty, on the sheet of paper mark the point where the beam

enters the prism (point d in Figure 3). Then mark the point where the beam exits

the prism (point e in Figure 3). Later you will draw a line between d and e to show

the path of the undiverted beam.

7. On the wall, mark the point where the undiverted laser hits (point b in Figure 3).

As long as the laser pointer stays fixed, this point should remain constant

throughout the experiment. Check it for each measurement.)

8. Now, add liquid to the prism. Rotate the prism so that the path of the refracted

beam within the prism (solid blue line from d to f in Figure 3) is parallel with the

base of the prism. When the prism is rotated correctly, mark the position of the

emerging beam on the paper on the wall (point a in Figure 3). On the paper on

the table, mark the point where the beam emerges from the prism (point f in

Figure 3).

9. Move the prism aside. Leave the paper taped in place.

10. Use a ruler to draw a line from point d to point e. This marks the path of the

undiverted beam.

11. Next, extend a line from point a (on the wall) through point f (on the table). To do

this, stretch a string from point a so that it passes over point f. Mark the point (c)

where the string crosses the line between d and e.

12. Measure the distance, x, between points a and b, and record it in the data table.

13. Measure the distance, L, between points b and c, and record it in the data table.

14. The distances that were measured define the angle of minimum deviation, θmd.

15

15. The ratio x/L is the tangent of the angle. To get the angle, use a calculator to find

the arctangent of x/L. (The arctangent of x/L means "the angle whose tangent is

equal to x/L.") Record the angle in the data table.

16. After calculating the angle of minimum deviation, use it to calculate the index of

refraction, n, of the liquid in the prism. (Figure 4.)

17. To check that your setup is working, plain water should have an index of

refraction of 1.334.

Figure 4. Simplified equation derived from Figure 5.

Figure 5. The equation to be used in finding the Refractive Index.

16

CHAPTER IV

Results and Discussion

Presentation of Data

The group conducted their research study on January 2010 at the College

Department Physics Laboratory, Holy Trinity College. This research study aimed to see

if sugar concentrations in different softdrinks can be determined using the dependence

of refractive index on the concentration by laser-based measurement.

Table 1. Control Variable

Concentration(Prism filled)

Index ofRefraction

SugarConcentration

(g)

X (cm) L (cm) qmd (n)

Air N/A N/A N/A N/A N/A

Water 1.33 0.00 35 40 11.4

Table 2. Experimental Variable

Concentration

(Prism filled)

Index ofRefraction

SugarConcentration

(g)

X (cm) L (cm) qmd (n)

Classic Coca-Cola

1.36 3.38* 39.4 84.2 25.2

Classic Pepsi-Cola

1.35 3.33* 39 84 25

Diet Coca-Cola 1.34 0.00* 37 83 24

Diet Pepsi-Cola 1.34 0.00* 37 83 24

*Based on the Table of Sugar Concentration in Drinks, EnergyFiend.com

17

Interpretation of Data

Results show that Classic Coca-Cola had 1.36RI, the highest refractive index

amount; 3.38 g of sugar concentration, 39.4 cm for X and 84.2 cm for L measurements;

and 25.2 for the minimum deviation (qmd). Classic Pepsi-Cola, on other hand, had

1.35RI; 3.33 g of sugar concentration, 39 cm for X and 84 cm for L measurements; and

25 for the minimum deviation. Subsequently, both Diet Coca-Cola and Pepsi-Cola had

1.34RI; 0 g of sugar concentration, 37 cm for X and 83 cm for L measurements; and 24

for the minimum deviation.

Discussion

According to Table 2, the prism filled with Classic Coca-Cola had the highest

number of refractive index, sugar concentration, X and L measurement, and minimum

deviation (qmd), with the prism filled with Classic Pepsi-Cola having the second most of

the amounts. Subsequently, both prisms filled with Diet Coca-Cola and Pepsi-Cola had

the same level of number of refractive index, sugar concentration, X and L

measurement, and minimum deviation, with both having the least amounts. Compared

to the control variables air and water, the four experimental variables proved to be

greater in amount.

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CHAPTER V

Summary, Conclusion and Recommendation

Summary

The materials used were collected. The experimental part was divided into two

parts: the Making of the Prism from Microscope Slides, and Measuring the Index of

Refraction of a Liquid, and were eventually performed at the College Department

Physics Laboratory, Holy Trinity College. In the experiment, a low-power laser pointer

with an output of 1mW and a wavelength of 630 to 680nm was used as a light source.

The beam was pointed at the prism filled with air (has no liquid inside), water, Classic

Coca-Cola, Classic Pepsi-Cola, Diet Coca-Cola, and Diet Pepsi-Cola. The different

variants yielded different points on the wall, as compared to the points where the

undiverted and the water-filled beam resulted.

Results showed that Coca-Cola Classic had 1.36RI, the highest refractive index

amount; 3.38 g of sugar concentration, 39.4 cm for X and 84.2 cm for L measurements;

and 25.2 for the minimum deviation (qmd). Other experimental variables had a lesser

value as compared to Coca-Cola Classic, as well as the control variable (water and air-

filled prism).

Conclusion

The researchers therefore conclude that Coca-Cola Classic had the highest

amount of sugar concentration, with the Classic Pepsi-Cola having the second highest

amount.

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Recommendation

The researchers further recommend the following:

1. Lengthen the period of the experimentation in order to perform

several trials to prove the accuracy of the results.

2. Test for other properties other than sugar concentrations.

3. Use other possible variables that can undergo Laser-based Index

of Refraction Method, like salt and sugar solutions, sodas and

other beverages, and other liquids.

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BIBLIOGRAPHY

Books

Silverio, Angelina A. “Exploring Life through Science: Physics” Phoenix PublishingHouse, Inc. pp. 371.

General References

"Table of Refraction." Microsoft® Encarta® 2009 [DVD]. Redmond, WA: MicrosoftCorporation, 2009

"Refraction." Microsoft® Encarta® 2009 [DVD]. Redmond, WA: Microsoft Corporation,2009

"Snell’s Law." Microsoft® Encarta® 2009 [DVD]. Redmond, WA: Microsoft Corporation,2009

Journals

Cuadra, Cristy Marie O., et al. “Phytochemical Testing of Barbados Cherry (Malphigiapunicifolia L.)” Holy Trinity College. Puerto Princesa City. 2008.

Canon, Gaea A. et al. “Phytochemical Study of Granadilla (Passiflora quadrangularis)”Holy Trinity College. Puerto Princesa City. 2008.

Caabay, Jenina Marie L., et al. “The Effect of Rice Washing, Fish Washing and DilutedUrine (male, female and pregnant) on the Growth of String Beans (Vitex Negundo)”Holy Trinity College. Puerto Princesa City. 2008.

Websites

“Refractive Index”. Wikipedia. Last Updated April 2, 2009. Date Accessed January2010. (http://en.wikipedia.org/wiki/Refractive_Index)

“Refractive Index of Some Liquids” Engineering Toolbox. Last Updated September2009. Date Accessed January 2010. (http://www.engineeringtoolbox.com/refractive-index-d_1264.html)

“Physics 20: Light Refraction – Snell’s Law” SaskEd. Last Updated October 2008. DateAccessed January 2010. (http://www.sasked.gov.sk.ca/docs/physics/u3c12phy.html)

“Optical Properties and Sugar Determination of Commercial Carbonated Drinks UsingPlasmon Resonance” Bnet. Date Accessed January 2010.(http://findarticles.com/p/articles/mi_7109/is_1_4/ai_n28396492/)

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Gnord. “WikiAnswers – What is the index of refraction of sugar” WikiAnswers. LastUpdated January 2010. Date Accessed January 2010.(http://wiki.answers.com/Q/What_is_the_index_refraction_sugar)

“Measuring Sugar Content of a Liquid with a Laser Pointer” Science Buddies. DateAccessed January 2010.(http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p028.shtml)

“Liquid (Physics) Science Fair Projects and Experiments” Julian Trubin. Date AccessedJanuary 2010. (http://www.juliantrubin.com/fairprojects/physics/liquid.html)

“Sugar in Drinks” Energy Fiend. Date Accessed January 2010.(http://www.energyfiend.com/sugar-in-drinks)

“Science Diliman – Journal 237-205” University of the Philippines Diliman. DateAccessed January 2010.(http://journals.upd.edu.ph/index.php/sciencediliman/article/download/237/205)

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Appendix