Shine it out

H1: Denser the solute filled within hollow prism, higher would be the refraction of laser beam, that is, light will bend more if it passes through a denser solution like vinegar or sugar than water.

Background information

How does a laser light work?

• "Laser"- Acronym for Light Amplification by Stimulated Emission of Radiation.

• LASER works by concentrating the light particles (Photons) in a single direction by exciting and vibrating particles through a glass or gas medium. So rather than spreading, the light is concentrated and thus goes much farther and in a straight direction than the ordinary light would.

Author: Live science

Source Website:

:https://www.livescience.com/physics-mathematics/how-do-lasers-work

Background information

PRISM: A 3D (three -dimensional ) transparent glass object,

which separates the passing light into seven different colours

(ROYGBIV) with Red being at the top and violet at the Bottom (See picture)

Properties of Prisms:

1. There are two identical faces ( called bases) & Several rectangular faces (lateral faces) and Edges where the faces meet. Depending upon the shape of bases, Prisms could be triangular (3 sides), rectangular (4 sides), pentagonal (5 sides) & Hexagonal (6 sides)

2. Measurement:

1. Volume: Multiplying the area of the base by the height

2. Surface Area: Sum of the areas of all faces

3. Height: Distance between its bases.

Author : vedantu.com

Source Website: https://www.vedantu.com/formula/prism-formula

Background Information

Interaction of Light & Prisms

When light passes through a prism, it bends and changes direction as it changes from one medium(air) to another (Glass). Snell’s Law states denser the material through which light passes, higher is the bending.

Now, the ordinary white light is made up of seven different colors (ROYGBIV- red, orange, yellow, green, blue, indigo, and violet.). When these colors pass through the prism, they bend at slightly different angles because they travel at different speeds. This is why we see a band of colors, like a mini rainbow ! These colors always appear in the same order since red light bends the least as it travels fastest, while violet bends the most as it travels the slowest.

[Author: Wonders of Physics.

Source Website: https://wonders.physics.wisc.edu/prisms/ ]

Background Information

Hollow Prism

A hollow prism is a special kind of prism that has a empty space inside. This space can be shaped like a cylinder or other geometric shapes.

Properties of Hollow Prism:

• the hollow part can be filled with air, gas, or other fluids.

• When white light passes through a hollow prism, it doesn't break into different colors (spectrum) because the light is passing from one medium (air) to the same medium (air) inside the prism. However, when filled with any liquid, the light bends twice.

[Author: Wonders of Physics.

Source Website: https://wonders.physics.wisc.edu/prisms/ ]

Hollow prism and light interaction.

Hollow Prism with No Fluid ( No Bending )

Hollow Prism with Fluid (Double Bending)

Background Information

How to calculate the refractive index (n) of any liquid using Snell’s Law

1. Measure the ratios: ab/bc

2. Calculate Angle of Minimum Deviation (dm): dm = tan inverse (ab/bc)

3. Apply Snell's Law: n = 2.00056 × sin[0.5(θmd + 60°)]

Where: (see the diagram)

ab: distance b/w the undeviated (un-filled) & deviated (Liquid filled) light beam

bc: distance b/w center of the prism & the deviated (refracted) light beam.

dm = Angle of Minimum Deviation

A = Angle of Incidence (60° in an triangular prism) & n = Refractive Index

Source: https://www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p028/physics/measuring-sugar-content-of-a-liquid-with-a-laser-pointer

Diagram of our project

Variables

Independent Variable

Different types of a solute (liquids with different densities) filled within hollow prism

Dependent Variable

How much does the laser beam bends when it enters & exits a hollow prism?

Controlled Variables - Ones kept as constant across the experiments:

• Temperature of a liquid (Room temperature)

• Laser light source (Laser beam)

• Prism type (Hollow Prism)

• Angle of the laser (Perpendicular)

• Distance from prism to screen (10 cm)

• Smooth surface box (Cardboard)

Procedure

1. Prepare three types of solutions

1. Plain Water

2. Sugar Water

3. Vinegar

2. Set up the Hollow Prism on a White Paper

3. Set up the Laser Light on the cardboard box & fix with tape

4. Put the three solutions in the Hollow prism One by One

5. Beam the Laser Light on the Hollow Prism perpendicularly

6. Measure the bending of light by observing the angles on White Paper

7. Repeat the experiment with different liquids

8. Note down the measurements in a table

Date: 1/26/2025

Observation

In this trial, we observed that when we used Plain Water,

ab = 4.5 cm

bc = 8.2 cm

Angle of Minimum deviation (dm) = tan inverse * 4.5/8.2 = 28.757

(Using Scientific calculator)

Refractive Index (n) = 2.00056 * sin (( 60 + dm)/2) = 1.332

Experiment: Trial 1

Data: (Plain Water)

Trials | Refractive Index

1 | 1.332

2 | 1.332

3 | 1.331

Mode Value : 1.332

Date: 1/26/2025

Observations/Notes:

In this trial, we observed that when we used Vinegar,

ab = 4.5 cm

bc = 7.8 cm

Angle of Minimum deviation (dm) = tan inverse * 4.5/7.8 = 29.981

(Using Scientific calculator)

Refractive Index (n) = 2.00056 * sin (( 60 + dm)/2) = 1.336

Experiment: Trial 2

Data: (vinegar )

Trial Attempt | Refractive Index

1 | 1.335

2 | 1.336

3 | 1.336

Mode Value : 1.336

Date: 1/26/2025

Observations/Notes:

In this trial, we observed that when we used Sugar Water,

ab = 5 cm

bc = 7.7 cm

Angle of Minimum deviation (dm) = tan inverse * 5/7.87 = 32.997

(Using Scientific calculator)

Refractive Index (n) = 2.00056 * sin (( 60 + dm)/2) = 1.383

Experiment: Trial 3

Data: (sugar water)

Trial Attempt | Refractive Index

1 | 1.383

2 | 1.384

3 | 1.387

4 | 1.383

Mode Value : 1.383

Results - Analysis

Look at your data and observations. Look for patterns and trends. Explain what happened in your experiment and what you found out:

• The trials and results depict how Snell’s Law operates in real life.

• When we change the solution, filled within the hollow prism, from less dense solutions like plain water to denser solutions like vinegar and sugar water, the angle of minimum deviation as well as the bending increases.

• Thus higher the refractive index of the medium, higher is the bending.

• Results show that plain water has the lowest density, followed very closely by vinegar solution (which is water plus acetic acid only) and then Sugar water, which has the highest density.

Conclusion

Testable question: How does the type of a solute in a liquid affects the diffraction pattern produced when a laser beam passes through a hollow prism filled with the liquid?.

Answer : On increasing the density of the solution, on changing the type of solute the diffraction pattern changes. More the denser the solution more the diffraction.

H1 (Hypothesis) is accepted as rightly predicted, denser the solute, higher the bending and data proves it to be so too.

Applications

• Refractometer- An instrument that uses Snell’s law to calculate the refractive index of liquids like we did it in our experiment.

• Measures how much light bends as it passes through a liquid. It's used to analyze the purity, concentration, or other properties of liquids. Various Industry Applications are as following:

• F&B ( Food and beverage) Industry

• Measuring the sugar content of fruit juices, sodas & jams (Candy)

• Measuring the salinity of sauces and marinades

• Measuring the alcohol or extract content of beer, wine, or spirits

• Medical Industry

• Analyzing urine for diagnosis

• Manufacturing Industry

• Mixing water-based cutting fluids (coolants and lubricants used with metalworking equipment)

Sources of Error

Do you think your results were reliable? Were there any other factors or conditions that could have affected the results of your experiment in unexpected ways?

What could have affected your results, that would need to be controlled differently if you were to repeat the experiment?

• Since on repeat trials, we got almost similar results, therefore experiment shows good reliability. Some potential sources of error, which need better control, could be as follows:

• Variations in Prism Angles

• Variation in Laser Light’s Angles

• Inconsistencies in quantity of solute in prisms

• Controlling these variables in future could further improve the experimental reliability.

I used the ideas from some of the past science fair link fo ideas and i also used some ideas from AI. AI also helped me learn some of the meanings. My mom, dad and uncle hepled get things clear.

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