PROPOSAL

LASER TECHNOLOGY PROJECT

BENDING OF LIGHT IN DIFFERENT CONCENTRATION OF DIFFERENT

MEDIUM EXPERIMENT

PREPARED BY:

CHE WAN NAJWA BINTI CHE WAN ZAKARIA

(AW 120102)

FATIN AFIQAH BINTI MUHAMAD PAUZI

(AW120144)

SITI HAJAR BINTI ROUSLANLUDDIN

(AW 120031)

SUPERVISED BY:

DR NOOR AZURA BINTI AWANG

DR ZAHARIAH BINTI ZAKARIA

FACULTY OF SCIENCE, TECHNOLOGY AND HUMAN DEVELOPMENT

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

2015/2016

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TABLE OF CONTENT 2-3

1 INTRODUCTION

1.1 Introduction 4

1.2 Background of Project 4

1.3Problem Statement 4

1.4 Objectives of the Project 4

1.5 Limitations/Scope of Project 5

2 LITERATURE REVIEW

2.1 Introduction 6

2.2 General Overview 6

2.2 Overview of relevant problem statement 7

2.3 Summary 8

3 METHODOLOGY

3.1 Introduction 9

3.2 Flow Chart of Methodology Process 10

3.3 Materials 11

3.3.1 Sugar

3.3.2 Salt

3.3.3 Fresh Water

3.4 Preparation of solution 12-13

3.4.1 Sugar solution

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3.4.2 Salt Solution

3.4.3 Fresh water

3.5 Pouring Process 13

3.6 Laser Testing 13

3.7 Observation 14

3.8 Data Collection 14

4 EXPECTED RESULTS 15

4.0 Result

5 CONCLUSION & RECOMMENDATION 16

5.1 Conclusion

5.2 Recommendation

References 17

Appendices 18-21

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INTRODUCTION

1.1 INTRODUCTION

This chapter are discussed about background of the project, problem statement,

objectives and scope of project.

1.2 BACKGROUND OF PROJECT

Bending of laser beam in different concentration of different medium is the main

focus in this experiment. First of all, the experiment are carried out to see how the light

bending in liquid by using Helium-Neon (HeNe) laser as a light source. HeNe laser is used

because they can emit visible light. While most lasers cannot efficiently emit visible light,

HeNelasers usually emit at 632.8nm and produce a red beam. They also have good beam

quality as their beams stay tightly focused even over long distances.

The experiment is carried out by using three solutions which are sugar solution, salt

solution and fresh water. Sugar and salt solution must in highly concentrated so that we can

see the light penetrate through the liquid and pour in the water tank layer by layer with fresh

water on the top. For the better result, do not shake or mix the solution once you pour the

sugar solution. In addition, we also can determine the refractive index of the different

medium. As we know,placing sugar solution along the bottom of a long water tankcreates an

index of refraction gradient with the greater index of refraction nearer the bottom of the tank.

A laser beam bends continuously in the sugar solution and reflects off the bottom of the tank.

1.3 PROBLEM STATEMENT

How does light bend in different concentration of different solution?

What is the index of refraction of different solution?

1.4 OBJECTIVES OF PROJECT

To observe bending of light in different concentration of different medium.

To determine the index of refraction, n.

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1.5 LIMITATIONS/SCOPE OF PROJECT

In this project, there have several scopes that we have limit when doing the experiment:

Solutions that we used are highly concentrated sugar and salt solution and fresh water.

The volume for all solutions and fresh water are about 500 ml to 1000 ml.

Clear water tank and must in rectangular shape as a container to pour the solutions

and see the bending of laser beam

Laser used is Helium-Neon (HeNe) laser

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LITERATURE REVIEW

2.1 INTRODUCTION

Bending of laser beam has linked with index of refractive. By using sugar solution

and fresh water only can create a mixture with a gradient refraction index. This is the

principle explaining the mirage, gradient index lenses and fiber. Mirage is a naturally

occurring optical phenomenon in which light ray are bent to produce a displaced image of

distant objects or the sky. When we properly poured, sugar solution will create a mixture with

a gradual refraction index. The bottom will have a higher refraction index than the top. When

a light beam travels inside, its direction will bend continuously. This situation is obeying

Fermat’s principle that stated the path taken between two points by a ray of light is the path

that can be traversed in the least time.

2.2 GENERAL OVERVIEW

The index of refraction is defined by Snell's Law which is a formula used to describe the

relationship between the angles of incidence and refraction when referring to light or other

waves passing through a boundary between two different isotropic media such as water, glass

or air.

where,

n1 and n2 are the refractive indices of the two media. It is apparent that the larger angle against

the normal direction must occur in the medium with the smaller refractive index.

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2.2 OVERVIEW OF RELEVANT PROBLEM STATEMENT

Refraction:

When we talk about the speed of light, we are usually talking about the speed of light

in a vacuum, which is 3.00 x 10^8 m/s. When light travels through something else such as

glass, diamond or plastic, it travels at a different speed. The speed of light in a given material

is related to a quantity called the index of refraction, n, which is defined as the ratio of the

speed of light in vacuum to the speed of light in the medium:

index of refraction : n = c / v

When light travels from one medium to another, the speed changes same with wavelength.

Although the speed and wavelength are changes, the frequency of the light will be constant.

The frequency, wavelength, and speed are related by:

An index of refraction is the ratio of the speed of light in a material to the speed of

light in a vacuum. Because light will slow down in every material, the wavelength gets

squished closer and the beam bends The higher the refractive index, the more a material will

bend a ray of light.

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2.3 SUMMARY

The change in speed that occurs when light passes from one medium to another is responsible

for the bending of light or refraction that takes place at an interface. If light is travelling from

medium 1 into medium 2, and angles are measured from the normal to the interface, the angle

of transmission of the light into the second medium is related to the angle of incidence by

Snell's law:

When light cross an interface into a medium with a higher index of refraction, the

light bends towards the normal. Conversely, light traveling across an interface from higher n

to lower n will bend away from the normal. This has an interesting implication: at some

angle, known as the critical angle, light travelling from a medium with higher n to a medium

with lower n will be refracted at 90°, in other words, refracted along the interface. If the light

hits the interface at any angle larger than this critical angle, it will not pass through to the

second medium at all. Instead, all of it will be reflected back into the first medium, a process

known as total internal reflection.

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METHODOLOGY

3.1 INTRODUCTION

In this chapter, all the components of the process involve in whole scope of study will

be explain in detail. This includes the description of material used, preparation of solutions,

pouring process, testing with laser, observation and data collection. In this process, the

materials involved are sugar, salt and fresh water. At the beginning, all the material involved

was placed in three different beakers and the appropriate measured amounts of materials

needed were described.

For the preparation of solutions, there were three solutions were prepared which are

sugar solution, salt solution and fresh water. While preparing the solution, it was important to

ensure the ratio of the solute and fresh water used in order to gain a good solution. At the

pouring process stage, a folded paper was used to reduce the speed of pouring and to avoid

the different solutions from mixing. A clear water tank was used to collect the solution. Next,

the effects of laser beam bending for different solutions concentration are carried out to be

testing with the used of He-Ne laser.

The observation is start by observing the bending of laser light on the three different

solutions with different concentration and refractive index. Then, the further studied on the

data collection which was more focusing on the bending of laser light beam as it pass through

the different solution’s concentration and refractive index. In overall, the overview of

experimental technique and process is simplified as refer to the flow chart in Figure 3.1.

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3.2 FLOW CHART OF METHODOLOGY PROCESS

Figure 3.1 : Flow Chart of Methodology Process

Basic Material

Laser Testing

Data Collection

Preparation of Solutions

Observation

Sugar + Salt + Fresh water

*Sugar solution ( sugar + fresh water )

*Salt solution ( salt + fresh water )*Fresh water

v*He-Ne laser ( Red, 633nm )

Pouring Process

*Binding effects on laser light

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3.3 MATERIALS

The material used in this experiment are salt, sugar and fresh water with measurement

of 1 kg of sugar, 400 g of salt and 1.5 L of fresh water . The material will be converted into a

different solution through a mixing process by using stirrer.

3.3.1 Sugar

Figure 3.2 : Sugar

3.3.2 Salt

Figure 3.3 : Salt

3.3.3 Fresh Water

Figure 3.4 : Fresh Water

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3.4 PREPARATION OF SOLUTION

3.4.1 Sugar solution

The first stages of sugar solution preparation is by dissolving 1 kg of sugar into 1.5 L

of water. For faster dissolving process, the temperature of water was set at about 50°C and

the mixture was continuously stirred until all the solute (sugar) was dissolved and the solution

turns into yellowish colour.

Figure 3.5: Sugar Solution

3.4.2 Salt Solution

The preparation of salt solution is by dissolving 400 g of salt into 1.5L of water. Same

as the preparation for sugar solution, the temperature of the water was also at 50°C. The

mixture was continuously stirred until the salt was dissolved and the solution become chalky.

Figure 3.6: Salt Solution

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3.4.3 Fresh water

The fresh water preparation was the simplest. Collect about 1.5L of pure and fresh

water from the pipe. Ensure that there was no obvious impurities in the water.

Figure 3.7 : Fresh Water

3.5 POURING PROCESS

At this pouring stage process, a folded paper was used while pouring the solution into

the water tank. This is to reduce the speed of pouring as to avoid the solution from mixing. At

first pour the fresh water, then the sugar solution and lastly the salt solution into the water.

After this process was finished, there were three layer of solution formed. In that layer

formation, sugar solution will be at the bottom of the water tank. Meanwhile, the salt solution

will be at the middle and fresh water was at the top.

3.6 LASER TESTING

The helium-neon (He-Ne) laser is usually constructed to operate in the red at about

633 nm. The reason to choose He-Ne laser because it was the most common and inexpensive

gas laser. Place the He-Ne laser close to the water tank. Ensure that there was no obstruction

which may affect the light beam. Be extra careful while handling with the laser as it might be

very sensitive. Do not point lasers directly in the eyes.

Figure 3.8 : He-Ne laser

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3.7 OBSERVATION

Observe the bending of laser light beam as the laser was slowly moved up and down

and passed through the solution. Observation was important to see the effect on the laser light

beam on the different concentration and refractive index. For more clear observation, the

observation was done in the completely dark room.

3.8 DATA COLLECTION

The data collected need to be analyses and conclude. The relationship must be carried

out. Data or result from the observation on how does light bend in sugar solution, salt

solution and fresh water, the light interaction with sugar or salt solution or index of refraction

change from material to material need to be explained precisely.

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EXPECTED RESULTS

4.0 RESULT

For the results, the laser light deflection for sugar solutions showed that deflection

strongly depends on the solutionconcentration, its density and weakly depends on the light

wavelength. Comparison between sugar and salt solutions showed that refraction of light

depends on the nature of the solute. The sugar solutions refract light more than salt solutions

of the same concentration and density. The light bending was observed for the sugar solution

with the strong concentration difference between the top and the bottom of the container. The

light bending disappeared after theconcentration became the same due to the diffusion.

Figure 4.1: The laser bending into the solution

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CONCLUSION & RECOMMENDATION

5.1 CONCLUSION

We can conclude that the light bends downward as it travels toward the bottom of the tank

through the sugar and salt solution. When light travels from a medium with a lower index of

refraction which is lower concentration into media with higher indices of refraction which is

greater concentrations the light bends towards the normal. The concentration gradient used in

the demonstration is gradual so the bending of light will be smooth. The light will reflect off

the bottom of the tank and show bending away from the normal as it rises into media with

lower indices of refraction.

5.2 RECOMMENDATION

1. Use the blocks. The purpose of the blocks is to raise the water tank so that we can see

that no light is refracted below it. The laser beam would be visible through the glass.

2. When preparing the sugar solution, do not interfere with the dissolving process. We

want a concentration gradient with the most concentrated part of the solution at the

bottom of the tank and the least concentrated part of the solution at the top of the tank.

3. Only use a low-power visible laser (a Class 1 or Class 2 laser) because the power

output and beam characteristics are such that they will not damage the eye.

4. Do not look into a laser beam of any type. Ensure that the beam cannot be reflected

into the eye at full intensity.

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REFERENCES

1. https://lecdem.physics.umd.edu/l/l4/l4-23.html

2. https://spectroscopy.wordpress.com/2011/04/10/bending-a-laser-beam/

3. http://sciencefair.math.iit.edu/projects/light/

4. http://buphy.bu.edu/py106/notes/Refraction.html

5. https://www.math.ubc.ca/~cass/courses/m309-01a/chu/Fundamentals/snell.htm

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APPENDICES

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