Category Archives: Vassar

Laser Refraction through Various Liquids

Xiaoxue Jiang

I’d wanted to do a project on lasers all along, given the few (if any) chances I’d get to do so after college. I was always fascinated by their technology and wanted to know how such an advanced, isolated manifestation of science would interact with certain elements of our world. I came up with testing laser refraction through liquids of varying colors and densities, as they would give me a good variety of samples in a consistent form.

Shown below is the basic set-up I used for the experiment. I used a power-meter set to milli-Watt units to measure the power output of the helium neon laser after its refraction through a liquid. This particularly striking substance creating the fluorescent effect is nothing but orange juice.

With this set-up, I collected the following data, making sure to include both distilled water and an empty vial as the control.

Refracting Material Power (mW)
None 3.734
Empty vial 2.885
Water 4.418
Green tea 2.133
Orange juice 0.002
Red water 4
Yellow water 3.375
Green water 0.012
Blue water 0.013

While the results were not as consistent as I’d hoped, I did find a few patterns in the data. Given that the color of the laser was red, I was not surprised by the incredibly low power levels of the laser refracted through green and blue, as it was most likely absorbed rather than reflected onto the power meter. Red water, in contrast, resulted in a high power reading thanks to the same scientific concept.

Orange juice was a different matter entirely, given its high opacity. Rose, who assisted me in the experiment, told me that the opacity scattered the laser light and therefore allowed very little through to the power meter, making its color largely irrelevant.

I’m also unsure as to why water yielded a higher reading than having simply nothing there to refract. With what I have, I can only attribute this to human error. By and large, the results were as predicted given what I knew about electromagnetic waves in the visible spectrum and the principles of absorption/reflection in color.

If I could redo this project, or have an additional six weeks, I would have definitely done multiple trials to ensure the accuracy of my data. There is a possibility that the curtains were not fully drawn to prevent outside light from affecting the reading. I would have also used more materials, perhaps even solid ones such as quartz or crystal if I could acquire it in time.

I am generally happy with the opportunity I was presented with to work with lasers in a safe and controlled environment. I enjoyed learning more about them (specifically the scattering phenomenon in an opaque liquid) and getting some hands-on experience in the scientific method.

Relation Between Light Intensity and EM Activity


My project was concerned with finding the relation between light intensity and electromagnetic activity at six different locations on Vassar College’s campus. The level of light intensity was found by use of a photo sensor. Electromagnetic wave levels were obtained by use of a RF Meter. These two variables were then analyzed at each respective location in order to ascertain the correlation between the two variables. This was done by calculating the coefficient of determination, or R squared value.


The coefficient of determination for the data was found to be 0.16. This means that while there is a positive correlation, it is a very weak correlation which is not statistically significant. This means that given the level of light intensity, it is unlikely that a person would be able to predict the level of electromagnetic activity and vice-versa.

Results vs Prediction

The results were contrary to my prediction. I predicted that light intensity and electromagnetic activity would have a significant correlation due to the fact that light is an electromagnetic wave itself, and therefore, hypothetically, more light would result in more electromagnetic waves. However, this experiment made it apparent that electromagnetic waves other than light have enough bearing on the total level of electromagnetic activity to result in there being no significant correlation between the two variables.

Science Learned

In carrying out this experiment I learned that there was an apparatus that could measure the electromagnetic wave activity passing through the air. I did not know that such a device existed. I am also very surprised that a device with this capability is inexpensive enough where an institution can own a large supply of them for students. I also learned that everything that exists in the universe has both an electric current and a magnetic field. Furthermore, I learned that the reason all matter has both an electric current and a magnetic field is due to the movement of electrons around an atom’s nucleus.

Relation with Current Technology

This experiment relates with current technology in a couple of ways. First, the RF meter is interesting in that it can be used to measure the electromagnetic waves of the Wi-Fi or Bluetooth coming off of phones and computers. This can be helpful in showing the amount of data necessitated by different applications. The other way this project relates is that there is a lot of concern by people that the waves given off by technology might be harmful to human health. However, the vast majority of scientists espouse the consensus that these waves are harmless.

What I’d Do Differently

If I were to redo this project, one thing I would do differently is utilize multiple RF meters to accrue data on electromagnetic wave levels. I would then take the average of these several readings to get the level for a location. The reason I would opt to do this is that the RF meter fluctuated greatly when obtaining a reading, which made me question its accuracy. Ideally, I would like to use RF meters manufactured by different companies so as to see if the different manufacturers’ devices fluctuate less than those possessed by Vassar’s Physics Department.

If The Project Continued an Additional 6 Weeks

If this project were extended for six additional weeks, there are a couple things I would do. First, I would add additional locations from which I would obtain data. I would do this so as to see if the correlation between light intensity and electromagnetic waves was stronger in locations other than those from which I obtained my measurements. Also, I would take measurements at all of my chosen locations at three different times between dusk and dawn. I would do this in order to see if the correlation between the two variables is weaker or stronger at different times of the night, when more or less people are awake and using electronic devices.