S'Milk on the Water

“S’milk on the Water”

Penetration of Light Through Water and Milk

By Lacey Bruske, and Will Lambeth

Period: 4A

Introduction

Review of Literature

Our experiment is based more on how light is refracted through a liquid substance. We must understand the way in which light reacts, and how to measure such a substance. In the basic Light Volume 1, it described light “consisting of individual particles which are emitted by light sources and which propagate through space in straight lines.” Better helping us understand that as the light is emitted through our source its Manipulating Light gives an in depth approach to how light is absorbed by substances, especially a liquid, such as milk and describes the process in which this occurs. In Photonic Crystals and Light Localization they cite that “the light localization of transmitted intensity with distance, is the absorption by the substance of the light.” Our light has to not only pass through water, which is in fact tap water, but also the milky substance, significantly reducing how many photons will pass through. We would use the science encyclopedia to cite in our main write up for basic definitions, and formulas when we discuss the speed at which light passes through a liquid, such as milk and water. The article in Science in the Making describes the way the beams penetrate substances, and are able to be identified. The internet site listed below was helpful in introducing new measurements and techniques on how to measure light, and the velocity of it once it has reached the liquid. It also gave a brief description of how to measure lost light due to absorption into the liquid.
Description of the Question
What effect will adding milk to a container of water have on the opacity of the solution, both when tested from straight on and from the side?
Independent variables: the ratio of milk to water in the solution, the angle at which the light hits the water
Dependent variable: the intensity (in lumens) of the light recorded on the other side of the solution by a sensor.
Back to Table of Contents

Hypothesis
We believe that if we shine a light at varying angles through a bottle containing varying amounts of milk, the amount of light picked up by a sensor on the other side of the bottle will decrease proportionally to the milk added when tested straight on because it will cloud the solution, but increase proportionally when tested from the side because the milk will refract more light to the sides.

Back to Table of Contents

Set-up Diagram

Will and I working on strenuous labor to construct our amazing physics project

My head is covered in glass!

Graphs

Data - Text tab delimited

Table of Contents

Materials

• 500 mL of Milk (There will be some extra)
• 600 mL of Water, preferably purified, otherwise tap water works
• A glass, a bottle worked best for the experiment we performed
• In order to replicate our experiment, you will need the apparatus we used, which guided the angles, as well as set up how our light fit to shine through our glass bottle.
• A light source with light powerful enough to get a reading
• Measurement in light, in our case we used photons and lumen.
• The measurement was also connected to the computer which read how many lux, then converted to lumen were being read.
• Beaker, measuring water and milk put into the bottle
• Paper, and pencil to record data

Table of Contents

Procedure
1. Set-up Apparatus, by installing the light fixture, as well as the bottle.
2. Cover sections with black paper so no apparent light can seep out.
3. Attach light sensor to computer for accurate readings.
4. Fill bottle to a tall enough point as is detected by the sensor (200 mL).
5. Set the lux recorder at the end of the apparatus to read the lux.
6. Record the number of lux or lumen detected with just water.
7. Prepare to pour milk in smaller increments, of about 10 mL and measure each time a new amount is poured in.
8. Shift the apparatus to a ten degree angle, and then read the sensor.
9. There will be times of trial and error, as we had in our experiment, in which case you must pour out all of the combined liquids and rinse.
10. Repeat steps 3 thru 6 until the sensor no longer records any increments lower that can be detected.
11. Record all of the data in order to compile an accurate graph.
12. Dismantle the apparatus, and clean out any area that has been contaminated by the milk, as it may contain an odor after use.

Back to Table of Contents

Analysis/Conclusion
Neither part of our hypothesis was supported by our data. Our first contention, that the milk would cause a decrease in the lumens detected when viewed straight on, seems to have been disproven, as our data shows a jump when small amounts of milk are added in the 0-degree category as well as the 5-degree category. The second part, that the intensity would increase as viewed from an angle, was also disproven, as after an initial jump the intensity in all three test categories fell as the milk concentration rose (the 10-degree category never even showed an initial jump).
The initial jump is by far the most interesting part of the data we collected. It seems to suggest that there is some refraction effect, and it's possible that the increments of concentration and angles we were using were simply too large to catch this effect in detail before the solution became overly clouded and overwhelmed any possible refraction. With smaller adjustments to the independent variables, it's possible that this experiment could be performed again and produce results fully in support of our hypothesis.
However, it's also possible that this was simply an anomaly, and the intensity will simply decrease as the solution becomes opaque. There are many sources for possible error: outside light leaking in to the sensor, the milk settling as the experiment progressed, and the temperature of the solution may all have impacted the data. The milk had also begun to curdle. Finally, our data suggests that all of the trials taper towards an intensity of 188 lumens as the concentration increases. While it is possible that this is simply due to the solution assuming the opacity of pure milk, it appeared to us that the light sensor we were using had a threshold at 188 lumens, and could detect nothing less intense than that. We believe that with a more accurate sensor, the data would continue to vary for each angle of measurement as the concentration approached 15%.

So, the experiment could be regarded as something of a failure, as the data managed to apparently disprove both of the contrasting portions of our hypothesis. The interesting spike in intensity we detected in both the 0- and 5-degree trials, however, leads us to think that more trials might result in a more favorable result for us. Though we did fail this time, with more equipment and a finer range of measurement it's very possible that our hypothesis will be vindicated.

Table of Contents

Bibliography
Davis, Edward A. Science in the Making. Taylor and Frances Inc.
Bristol, PA. 1997.

Haken, H. Light Volume 1. North-Holland Publishing Company. Amsterdam. 1981.

Service, Robert F. http://www.sciencemag.org/cgi/content/summary/292/5518/825a 2001, May 4. Vol. 292. no. 5518, pp. 825 - 826

Soukoulis, Costas M. Photonic Crystals and Light Localization in the 21st Century. Kluwer Academic Publishers. Dordrecht. 2001.

Darlene L. Manipulating Light: Reflection, Refraction And Absorption.
Random House. 1987.

Back to Table of Contents