Step 1: Gather Your Materials
• Water, this will serve as the standard
• Light source
• Container for Gatorade, preferably a clear semicircular one
• Track to stabilize materials
• Slit plate and mask, this will focus the light to make it easier to see the angles
Step 2: Setting Up the Experiment
After you are done, you should have something similar to the picture above.
Step 3: Finding the Angle
Turn on the light and adjust the protractor so that the light hits the container parallel to the normal axis (the bold line in the picture above). If the light is difficult to see, you may need to turn off the lights. If you have set up the experiment properly, the light should focus into a line and exit the container at an angle. In the picture above, you can see that the light bends to one side after it passes through the water.
If your protractor reads 0 degrees at the normal, then the angle of refraction can be found by looking at where the light is on the protractor. However, if it does not, then you can find the angle of refraction by calculating the difference between the angle marked by the light and 90 degrees.
Now, rotate the protractor (with the container on top) ten degrees at a time. At each interval of ten degrees, record the angle obtained, and rotate to the next angle. At the angle where the refracted light is no longer visible, or is perpendicular to the normal. Another way to check is if beyond this angle, you achieve total internal reflection. Record this angle as the critical angle. Continue beyond this point up until you reach 90 degrees, still going by 10 degree intervals.
After this, empty your container, and fill it with your gatorade. Repeat the experiment and note the critical angle. It may be different!
Step 4: Calculating Index of Refraction
Initial angle = 20, Refracted angle = 30
n1*sin(θ1) = n2*sin(θ2)
n1*sin(20) = 1*sin(30)
n1*0.343 = 1*0.5
n1 = 1.458
Step 5: Our Data
50, critical angle
Rain Strawberry Kiwi Gatorade:
50, critical angle
Here we see that the data is slightly different, yet not very much so. This indicates that the gatorade is very similar to water, thus perhaps containing a large percentage of water.