The Laws of Reflection

Understanding Reflection

Whether a mirror is flat or curved, light follows strict rules when it bounces off. These are called the Laws of Reflection.

Key Terminology

1. Incident Ray: The ray of light falling on the surface.
2. Reflected Ray: The ray of light bouncing back.
3. Normal: An imaginary line drawn perpendicular ($90^\circ$) to the surface at the point where the light hits.
4. Angle of Incidence ($i$): Angle between the Incident Ray and the Normal.
5. Angle of Reflection ($r$): Angle between the Reflected Ray and the Normal.

The Two Laws

1. First Law: The angle of incidence is equal to the angle of reflection. $\angle i = \angle r$

2. Second Law: The incident ray, the normal at the point of incidence, and the reflected ray all lie in the same plane.

   • Experiment: If you reflect light using a mirror on a sheet of paper, and then fold the paper where the reflected ray is, the ray disappears from the folded part. This proves they must be on the same flat surface.