Finding the Refraction of a Gummy Bear

Introduction: Finding the Refraction of a Gummy Bear

An optics class experiment shows the difficulty of finding the  refraction of a gummy bear.

To perform this experiment, you will need:
- An optics bench
- A ray table and base
- A light source( we used a laser)
- Gummy Bears

We chose gummy bears because we were interested in finding the material that make gummy bears chewy.

Pd. 1 Mallow, Peter Chen, Mina Tran

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Step 1: How to Find the Angle of Refraction Using Snell's Law

The angle of refraction is the angle in which light travels after passing from one medium to another. 

Light bends at a different angle because it travels at a different speed through different materials with different refractive indexes.

Th angle of inflection is the angle in which the light enters the new medium while the angle of refraction is the angle it becomes once it has entered the new medium.

Snell's Law uses the proportion between the angle of refraction and inflection and the refractive indexes of a material to solve for the unknown variable. The refractive index could further be used to find the material in which the light is passing through.

Snell's law:
(the refraction index of the material)   x    sin(inflection angle)   =   (the refraction index of the material)    x      sin(refraction angle)

Step 2: Setting Up Your Experiment

Attach the optics bench and ray table, then place the gummy bear onto your ray table. In order to measure the inflection angle, it is best to have the back/flat side of the gummy bear facing the laser, since it provides a flat surface for the laser to pass through. These items need to be placed at a height in which the laser will pass through the gummy bear, we used a text book to elevate the optics bench. Once that is done, turn on your laser and measure the angle of refraction at angles of inflection that are multiples of 10.

When we reached this step, we found that once the light hit the gummy bear, it was scattered, and therefore did not produce a refraction angle.

Step 3: Problems With the Gummy Bear and Possible Solutions

We detected a few problems with using a gummy bear. The first of which is the frosted outer coating of the gummy bear. This made it difficult for light to pass through the gummy bear so we rinsed it under water, washing away the coating, and exposing a clearer medium. However, the shape of a gummy bear is not ideal for this experiment either, because of its feet. We would need a concave shape in place of the feet for the optimal refraction angle to be shown. At first, we used scissors to cut a concave edge, which allowed  a ray of light approximately 2 mm long to pass through. However the gummy bear was extremely small once we cut it and would not stay upright. So we decided to melt down some gummy bears of the same color and pour the melted gummy bears into a container with a flat edge on one side and a concave edge on the other. But once melted down, the gummy bears became extremely opaque and light could not pass through.

Step 4: Possible Solutions

Although we could not continue the lab due to a time limit in class, there are many things that we could have done differently. It is possible that we could have simply bought a larger gummy bear and cut the precise shape in order for the gummy bear to stay upright on the ray table. Or we could have made use of the smaller cut gummy bear and simply used a flat edge to approximate the angle of refraction, constantly readjusting the gummy bear to stand upright.

Either way, we will definitely try to complete this experiment in the future, since it would be interesting to know what gummy bears are actually made of.

This was a good experiment because it showed us the difficulty of setting up an experiment. It also forced us to be creative in finding solutions to make the experiment work.

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    Teresa Mallow
    Teresa Mallow

    7 years ago on Step 4

    Well - the gummy bear wins this time - but you have given future students some good background to build on. :)