Georgia State University
Index of Refraction and Total Internal Reflection
Ray box, two different transparent blocks, two letter size white pages, pencil, protractor, two
nails, and graph paper.
Understanding image formation due to refraction.
Finding the index of refraction of a transparent material.
Observing total internal reflection and experimentally finding critical angle.
Part 1: Introduction and Predictions
Take a look at the transparent cube in which you find a vertical strip on one of its sides. If you look
through the opposite side of the cube as shown in the side view below, you see the strip (image of the
strip) appear to be closer to you than the actual strip (object) because the light coming from the strip is
refracted as it exits the cube to get to your eye. We will use the method of parallax as you used in the
tutorial to locate the image and compare the location of the image with the location of the object.
Light scattering off of the strip (the object) first travels through the block (medium 1) and then travels
through the air (medium 2) to get to your eye.
What is the index of refraction of air?
Is the index of refraction in medium 1 (block) larger or smaller than medium 2 (air)?
Do you think the image appears to be closer to you or farther away than the object?