Snell's Law with Large Blocks Available to Purchase

The introductory physics lab curriculum usually has one experiment devoted to the study of the refraction of light. The most obvious way to study the refraction of light is to lay a transparent block down on the lab bench and aim a laser beam horizontally at the block so that it refracts twice—inward upon entering the block and outward upon exiting. The vendors that provide us with lab equipment (Sargent-Welch, PASCO, Fisher Scientific, and Frey Scientific to name a few) sell acrylic blocks for this very purpose, but these are either too small or they are too expensive. If students are going to measure angles of incidence and refraction, the blocks should be larger than the typical student protractor, which has a radius of 3 in (≈ 7½ cm). These blocks are just not large enough. They are generally not thick enough either so that the beam from a typical laser passes over them and not through them. The vendors mentioned above do sell blackboard optics kits that contain, among other parts, three blocks that are large enough—on the order of 10 to 20 cm. Unfortunately, these kits cost more than $1000.