Light Refraction Lab Final Write-Up When light passes through any obstacle, it is affected in different ways, especially when the obstacle is transparent. In this lab, the objective was to show students what happens when light passes through water. “When light refracts into a substance in which it must slow down, the light ray will bend toward a line perpendicular to the surface it strikes” (Wile). Water forces a light ray to slow down, and so the light ray will bend. (Similarly, if a light ray passes through an obstacle that forces it to speed up, it will bend away from the line perpendicular to the surface it strikes.) This is the principle of refraction. Students were supposed to see this bending of light. In general, the class did indeed