Physics · Ch 6 — Optics
Reflection
Reflection
Reflection is the bouncing back of light into the same medium when it strikes a reflecting surface. A silvered mirror reflects almost 90% of the light incident on it. The two laws of reflection state: (a) the incident ray, the reflected ray, and the normal drawn at the point of incidence are all coplanar (lie in one plane); and (b) the angle of incidence (between the incident ray and the normal) equals the angle of reflection (between the reflected ray and the same normal), . These laws hold at every point of any reflecting surface, whether it is perfectly flat or curved. A flat, polished surface reflecting a bundle of parallel incident rays sends them out still parallel to one another -- regular reflection. A rough, irregular surface reflects the same parallel bundle out in many different directions -- irregular (diffuse) reflection -- even though the law …
What this figure shows. A ray AO strikes a silvered plane mirror at point O, making angle of incidence i with the normal ON, and leaves as the reflected ray OB, making angle of reflection r with the same normal. The diagram visually anchors the law i = r and shows that the incident ray, the normal ON, and the reflected ray OB all lie in one flat plane -- if they did not, the mirror equation and every later ray-tracing …
What this figure shows. Two bundles of parallel incident rays are shown striking two different surfaces. On a smooth, flat surface the reflected rays emerge still parallel to one another (regular reflection, as from a polished mirror). On a rough, irregular surface the reflected rays emerge scattered in many different directions even though every single ray still obeys i = r at its own point of incidence (irregular or diffuse reflection, as from paper or an unpolished wall) -- the law of reflection is a strictly local, point-by-poin …