Materials List: Make That Invisible!
Refractive Index Matching

For the teacher-led class demonstration:

Each group needs:

For Part 1, each group needs:

  • laser pointer
  • print out of a polar graph; such as the example graphs found at the University of South Florida's Florida Center for Instructional Technology ClipArtETC website at
  • (optional but recommended) plastic sheet protector to protect the paper polar graph from spills
  • clear tape
  • semicircular hollow acrylic block, 12 cm diameter x 2.5 cm high, available (part# RCSC01) at Nova-Tech International at
  • ~50 ml water
  • ~50 ml glycerin (or vegetable oil, such as Wesson), such as ACS grade, 4-liter bottle of glycerin (catalog # S25342D) from Fischer at; glycerin is preferred because it is the same color as water so students will not realize at first that the two liquids are different, and it is soluble in water, making clean-up easier

Photo shows four glass vials in holes cut in a rack made of cardboard. Vials labeled W1, W2, G1, G2.
Figure 2. Sample setup. The W2 and G2 sample containers use the 6-inch Pyrex glass tubes.
Copyright © 2013 Marjorie Hernandez, RET Program, College of Engineering, University of Houston

For Part 2, each group needs:

To share with the entire class: