Reflection and refraction are demonstrated using a red beam emitted by a diode laser (635 nm wavelength). The beam is incident on the top side of an acrylic block. Some light is reflected back into air and some light enters the block and refracts (bends). The beam is then reflected at the bottom side and refracted again at the top side of the block. The angles of incidence and refraction are related through the Snell's law and depend on the refractive index of the block. Note the difference between the angles of reflection and refraction.