1. Angle of Incidence = Angle of Reflection:
* When a ray of light hits a smooth surface like a mirror, it changes direction. The angle between the incoming ray (incident ray) and the perpendicular line (normal) to the surface is called the angle of incidence.
* The angle between the reflected ray and the normal is called the angle of reflection.
* The first law of reflection states that these two angles are always equal.
2. Incident Ray, Reflected Ray, and Normal Lie in the Same Plane:
* The second law of reflection states that the incident ray, the reflected ray, and the normal to the surface at the point of incidence all lie in the same plane.
How This Leads to Retracing:
* Imagine a ray of light traveling from a point A towards a plane mirror. It hits the mirror at point B.
* According to the laws of reflection, the angle of incidence (∠i) at point B will be equal to the angle of reflection (∠r).
* Now, draw a line from point A to the point where the reflected ray intersects the normal (point C).
* Since ∠i = ∠r, triangle ABC will be an isosceles triangle (AB = AC).
* Therefore, the path of the reflected ray will be symmetrical to the path of the incident ray.
* This symmetry ensures that the reflected ray will travel back along the same path it came from, effectively retracing its path.
In essence, the laws of reflection ensure that the angle of incidence and reflection are equal, forcing the reflected ray to follow a symmetrical path back towards the source.
