When light rays strike a mirror, the law of reflection governs their behavior. According to the law of reflection, the angle of incidence (the angle between the incident ray and the normal to the mirror) is equal to the angle of reflection (the angle between the reflected ray and the normal to the mirror). This law ensures that the reflected rays maintain a specific relationship with the incident rays.
When parallel rays of light strike a mirror, they all follow the law of reflection independently. Each incident ray obeys the law of reflection, and as a result, each reflected ray will be reflected at the same angle to the normal as the incident ray. Due to the parallel nature of the incident rays, the reflected rays will also be parallel to each other.
However, it's important to note that when we refer to rays of light, we are simplifying the behavior of light. In reality, light is composed of individual photons, which exhibit wave-particle duality. The parallel rays are a representation of the path of the photons, which can be understood as wavefronts in the context of light waves.
So, when parallel rays of light strike a mirror, the individual photons within those rays follow the law of reflection, resulting in the reflected rays. These reflected rays appear to come out from the mirror, but in reality, they are extensions of the incident rays following the same angle of reflection.