How do Solutes Affect a How do Solutes Affect a Solutions Angle Of Solutions Angle Of

Refraction?Refraction?

By, Prajwal KeranahalliBy, Prajwal Keranahalli

BackgroundBackgroundSnell's Law describes the physics of refraction. The Snell's Law describes the physics of refraction. The

index of refraction of a liquid depends on the index of refraction of a liquid depends on the density of the liquid. Dissolving sugar in water density of the liquid. Dissolving sugar in water results in a solution with density greater than results in a solution with density greater than that of water alone. Since sugar water is more that of water alone. Since sugar water is more dense than plain water, sugar water should dense than plain water, sugar water should have a higher index of refraction than plain have a higher index of refraction than plain water. water.

More BackgroundMore Background

Density of the solutes that I am going Density of the solutes that I am going to use:to use:

Baking Soda: 2.20 g/cm3 Baking Soda: 2.20 g/cm3

Salt: 2.16 g/cm3Salt: 2.16 g/cm3

Sugar: 1.5620 g/cm3 Sugar: 1.5620 g/cm3

HypothesisHypothesis

If the solute is baking soda, then the If the solute is baking soda, then the index of refraction of the solution will index of refraction of the solution will be greater, because baking soda has be greater, because baking soda has more density than salt and sugar, more density than salt and sugar, and greater density results in a and greater density results in a greater angle of refraction. greater angle of refraction.

Independent Variable/ Dependant Independent Variable/ Dependant Variable/ ControlsVariable/ Controls

Independent Variable: The SoluteIndependent Variable: The Solute

Dependant Variable: The Index of RefractionDependant Variable: The Index of Refraction

Control:Control:The Index of Refraction in water with no solute(0.4)The Index of Refraction in water with no solute(0.4)

Controls: Controls: The Type of ContainerThe Type of ContainerThe Type of WaterThe Type of WaterThe Type of LightThe Type of LightThe Amount of Each SoluteThe Amount of Each Solute

MaterialsMaterials A Laser Pointer A Laser Pointer 2, 1”×3” pieces of glass2, 1”×3” pieces of glass CardboardCardboard Measuring CupMeasuring Cup 100 mL of Salt, Sugar, and Baking Soda100 mL of Salt, Sugar, and Baking Soda A Graphing CalculatorA Graphing Calculator Electrical TapeElectrical Tape Epoxy glueEpoxy glue TapeTape 400 mL of Water400 mL of Water Glass CutterGlass Cutter 12in. of String12in. of String Tape measureTape measure Graph PaperGraph Paper Tooth PicksTooth Picks

ProceduresProcedures1.1. Cut your 1”×3” glass piece into 3 equal parts using a glass cutter. Cut your 1”×3” glass piece into 3 equal parts using a glass cutter.

Complete this step with adult supervision.Complete this step with adult supervision.

2.2. Arrange the 3 pieces of glass to form an equilateral triangular prism. Arrange the 3 pieces of glass to form an equilateral triangular prism. Glue it together using epoxy glue. Allow it to set.Glue it together using epoxy glue. Allow it to set.

3.3. Glue the prism on top of another 1”×3” glass piece. Allow it to set.Glue the prism on top of another 1”×3” glass piece. Allow it to set.

4.4. Take your laser and shine it perpendicular to the wall, place the empty Take your laser and shine it perpendicular to the wall, place the empty prism in front of the beam (the beam should not be diverted) and record prism in front of the beam (the beam should not be diverted) and record where the beam hits the prism and wall. where the beam hits the prism and wall.

5.5. Make 3 solutions by mixing 50 mL water with 0.25 teaspoons of Salt, Make 3 solutions by mixing 50 mL water with 0.25 teaspoons of Salt, Sugar, and Baking Soda.Sugar, and Baking Soda.

6.6. Pour one of your solutions into the prism until it is almost full.Pour one of your solutions into the prism until it is almost full.

7.7. Shine the laser through the prism and record where the light hits the Shine the laser through the prism and record where the light hits the prism and wall.prism and wall.

8.8. Repeat steps 1-7 with the other solutions Repeat steps 1-7 with the other solutions

To Find the Index of RefractionTo Find the Index of Refraction

1.1. Measure the distances of X and L (indicated on the diagram), it will define the measure of minimum deviation Measure the distances of X and L (indicated on the diagram), it will define the measure of minimum deviation which will be used to find the index of refraction.which will be used to find the index of refraction.

2.2. Also find the distance between segment CA Also find the distance between segment CA

3.3. Use X and L to find the arctangent. Opposite/Adjacent=X/L=measure of angle of minimum deviation=Use X and L to find the arctangent. Opposite/Adjacent=X/L=measure of angle of minimum deviation=ØmdØmd

4.4. Plug the angle of minimum deviation into the equation:Plug the angle of minimum deviation into the equation:2.00056sin(0.5(2.00056sin(0.5(Ømd+60))Ømd+60))this will give you the index of refraction.this will give you the index of refraction.

MeasurementsMeasurements

SugarSugar SaltSalt Baking Baking SodaSoda

134 mm.134 mm. 220.2621 220.2621 mm.mm.

164.0914 164.0914 mm.mm.

274 mm.274 mm. 272 mm.272 mm. 263 mm.263 mm.

312 mm.312 mm. 364 mm.364 mm. 310 mm.310 mm.

28.57 28.57 °° 41.65°41.65° 31.9631.96°°

XX

LL

Segment Segment CACA

ØmdØmd

No Solution

Baking Soda SaltSugar

Where Laser hit the Wall

Water

Data TableData Table

Type of Type of Solute in Solute in the the SolutionSolution

Solutions Index of RefractionSolutions Index of Refraction

Trail 1Trail 1 Trail 2Trail 2 Trail 3Trail 3 AverageAverage

SugarSugar 0.6 0.6 0.60.6 0.50.5 0.560.56

Baking Baking SodaSoda

1.81.8 1.91.9 1.81.8 1.831.83

SaltSalt 1.11.1 11 1.21.2 1.11.1

GraphGraph

0

0.5

1

1.5

2

Sugar

Baking Soda

Salt

Water

Type of Solute in the SolutionType of Solute in the Solution

So

luti

on

s In

dex

of

So

luti

on

s In

dex

of

Ref

ract

ion

(A

VG

.)R

efra

ctio

n (

AV

G.)

Type of Solute V.S. the Solutions Index of Refraction

ConclusionConclusionSolutions with higher density had greater index of Solutions with higher density had greater index of refraction. My hypothesis was supported through the refraction. My hypothesis was supported through the data. Baking soda which had the most density had more data. Baking soda which had the most density had more refraction than salt and sugar. It had a refraction of refraction than salt and sugar. It had a refraction of 1.83 while salt was 1.1 and sugar was 0.56. And the 1.83 while salt was 1.1 and sugar was 0.56. And the refraction of all the solutes was greater than the refraction of all the solutes was greater than the refraction water which was 0.4. So it is proven that an refraction water which was 0.4. So it is proven that an increase in density does result in a greater index of increase in density does result in a greater index of refraction. I already knew that substances refract light refraction. I already knew that substances refract light but this experiment explained to me why this happens but this experiment explained to me why this happens and why some substances refract more light than and why some substances refract more light than others. I could have improved my experiment by others. I could have improved my experiment by constantly replacing my lasers batteries so that I so that constantly replacing my lasers batteries so that I so that is could get more consistent measurements. A good is could get more consistent measurements. A good follow up experiment would be to test how different follow up experiment would be to test how different concentrations of solute in a solution would affect index concentrations of solute in a solution would affect index of refraction.of refraction.

Math Behind the Experiment 1Math Behind the Experiment 1

Angle of Minimum Deviation

X

L

Math Behind the Experiment 2Math Behind the Experiment 2

X

L

Used for Sine

Segment CA

Used for Arctangent

Math Behind the Experiment 3 Math Behind the Experiment 3

Ø = Arcsine = opposite/hypotenuseØ = Arcsine = opposite/hypotenuse

Ø = Arctangent = opposite/adjacentØ = Arctangent = opposite/adjacent

Ø = Arccosine = adjacent/hypotenuseØ = Arccosine = adjacent/hypotenuse

Sine = opposite/hypotenuseSine = opposite/hypotenuse

Tangent = opposite/adjacentTangent = opposite/adjacent

Cosine = adjacent/hypotenuseCosine = adjacent/hypotenuse

*(Sohcahtoa)*(Sohcahtoa)