What principle states that the angle of incidence is equal to the angle of reflection?

The principle that states the angle of incidence is equal to the angle of reflection is known as the Law of Reflection. This fundamental concept is applicable in optics, particularly when light interacts with reflective surfaces. It means that when a ray of light strikes a surface, the angle at which it approaches the surface (the angle of incidence) will be equal to the angle at which it bounces away from the surface (the angle of reflection). This relationship is crucial in understanding how mirrors and other reflective surfaces work, as it helps predict how light will behave when it encounters such surfaces.

In contrast, the Law of Refraction pertains to how light bends as it passes from one medium to another, which is not relevant to the relationship between incident and reflected angles. The principle of conservation of energy is a broad principle that applies to all physical processes, including those involving energy transfer, but does not specifically address reflection. Similarly, the principle of wave-particle duality relates to the behavior of particles like photons, illustrating their dual nature in exhibiting both wave-like and particle-like properties, rather than focusing on reflection. These concepts, while significant in physics, do not describe the behavior of light in relation to reflection, making the Law of Reflection the correct and relevant principle.