Laser Pointers and Index of Refraction

This was an interesting lab to work on because it was the first opportunity where I had so much control in the experiment. I was able to choose which project I wanted to work on, what aspect of lasers and optics I wanted to study, and how I wanted to study it.

This project analyzes Snell's Law and the Index of Refraction. It is accomplished by studying the path a laser pointer would take. The laser pointer was sent through a series of different media that had different indexes of refraction. Pictures were taken at each condition to demonstrate the laser's reaction to different media.

Snell's law can be seen in all aspects of life. My choice of examining it was through a fish tank and a laser pointer. Any time that one looks at an object passing though two different media and accepts that has accepted Snell's Law. For instance when you have an object that passes through air and then into water the object is expected to look as if it has bent slightly. This is because the object is passing through both the media of air and water. The object will bend at a certain angle perpendicular to the point where the two media meet.

The object that was used in this experiment was a laser pointer and the different media were different concentrations of sugar water, varying from pure sugar to pure water with various ratios in between. The laser gives a very clear bend because it is a thin beam of light. This bend of a ray of light is known as refraction. Refraction has been represented with the formula:

Setting Up The Experiment

DAY 1:

Pouring in the corn syrup to a beaker already filled with water.

It is evident how the corn syrup right away sinks down to the bottom pushing the water to the top.

Mixing it together so that it can be ready to be added to the fishtank.

The corn syrup and the water have been mixed. It is now ready to be poured into a tank that has already been partially filled with water. A funnel was used to pour in the mixture to create minimal mixing between the water and the corn syrup in the tank. For the most accurate bendings in the laser a strong difference between medias are necessary.

The division between the pure water and the corn syrup/water mixture is very visible. It is at the 2 1/8 inch mark.

Now... The fun part!!!

The experiment has been set up so now the laser pointer is shone through the tank at different angles. All different effects were recorded through pictures because this is a visual phenomena. Click on each of the pictures for a full view and a description.



DAY 2:

Many observations could be made on the second day about the changes in the appearance of the fish tank. On the first day the corn syrup and water mixture was poured very carefully with the use of a funnel. Small amounts of diffusion is inevitable but for the experimental purposes it is tried to be kept at a minimal. The state of the tank is not permanent. In time the water at the top of the tank will blend together with the corn syrup/water mixture.

Click here to see the blending and the changes that resulted in the refraction of the laser beam.

Interesting Links:

Snell's Law Demo

Snell's Law Explanation

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Created by:
Jennifer Marie Nierer