Final answer:
Refraction occurs when a beam of light passes from one medium to another, causing it to bend. The light will bend towards the normal if entering a denser medium. Some light is also partially reflected, and when interacting with a thin film, interference patterns can occur.
Step-by-step explanation:
When Calvin shines a thin beam of light onto a material, and it refracts, we are dealing with the physics concept of refraction. Refraction is the change in direction of a light ray when it passes from one medium to another. At the boundary between two different media, the light beam changes speed, causing it to bend either towards or away from the normal (the line perpendicular to the surface). The amount of bending depends on the indices of refraction of the two media and the angle of incidence. If the light is moving from a less dense to a more dense medium, like air to glass, it will bend towards the normal. During this process, some light is also partially reflected. This interaction can lead to interference patterns if the light is striking a thin film, with effects that depend on the film's thickness and the media's refractive indices.
In the scenario provided, if the material is a thin film, the light beam (ray 1) hitting the material will be partially reflected and partially refracted at the top surface. The refracted ray inside the material can be partially reflected again at the bottom surface, emerging as ray 2. These two rays can interfere, resulting in phenomena such as iridescence.