The angle of incidenceThe angle of incidence is the angle between an incident ray of light (or any other wave) and the normal, which is an imaginary line perpendicular to the surface… is the angle between an incidentAn unplanned event or occurrence that has the potential to cause harm, damage, or disruption to people, the environment, or assets. Incidents can range in sever… ray of light (or any other wave) and the normal, which is an imaginary line perpendicular to the surface at the point of incidence. It is denoted by the symbol "i." The angle of incidence is measured in degrees or radians.