Measuring Density by Bending Light

Observe Bending of Light in Different Materials

  1. On your computer, go to the PhET Bending Light simulation on the Internet at phet.colorado.edu/en/simulation/bending-light.
  2. Go to the Intro section of the software.
  3. Turn on the laser in the simulation by clicking on the red button.
  4. Adjust the index of refraction of the material in the lower half of the simulation. Observe the difference in bending of the laser beam as you change the index of refraction.
  5. Fill in values in the table below based on observations of the computer simulation. 
    1. Set the index of refraction of the bottom material in the simulation to each of the following three values: 1.20, 1.33, and 1.50.
    2. For each value of index of refraction, fill in the material and the amount of bending in the table below.
    3. Rank the amount of bending as "least", "most", or "medium."
Bottom MaterialIndex of Refraction (bottom)Amount of Bending
 1.20 
 1.33 
 1.50 

Estimate Density of Three Circular Prisms

  1. On your computer, go to the PhET Bending Light simulation on the Internet at phet.colorado.edu/en/simulation/bending-light.
  2. Go to the Prisms section of the software.
  3. Turn on the laser in the simulation by clicking on the red button.
  4. Drag a prism with a circular cross section, from the selection of prism shpes at the bottom of the screen, up into the laser's path.
  5. Change the index of refraction of the circular prism. Observe how the path of the light changes.
  6. Try to match each of the diagrams below, then fill out the table below the diagrams.
    1. Can you determine the material that the circular prism is made of in each of the diagrams?
    2. Based on what you know about density and index of refraction, can you guess which circular prism has the lowest density? the highest?

Refraction through circular prism: Example A

Refraction through circular prism: Example B

Refraction through circular prism: Example C

DiagramCircular Prism MaterialEstimated Density (most dense, least dense, medium)
A  
B  
C