Reflection:

Ancient people certainly knew regarding reflection. It would not take an smart creature very long to figure out that the "phantom in the pond" was really a visual image of him or herself. Any smooth, shiny surface reflects a few of the light which strikes it. When the surface is perfectly flat, absolutely shiny, and reflects all the light that strikes it, then any ray which encounters the surface is reflected away at similar angle at which it hits. You know the expression, "The angle of incidence equals the angle of reflection." This theory, termed as the law of reflection, is illustrated in figure given below.

Figure: Whenever a ray of light is reflected from a shiny, flat surface, and the angle of incidence is equivalent to the angle of reflection. Here both of the angles are represented by q.

In optics, the angle of incidence and the angle of reflection are together measured associative to a common line (also termed as an orthogonal or perpendicular). In the figure given below, these angles are represented by q and can range from 0°, where the light ray hits at a right angle in respect to the surface, to nearly 90°, a grazing angle associative to the surface.

When the reflective surface is not absolutely flat, then the law of reflection still exerts for each ray of light striking the surface at a particular point. In such a situation, the reflection is considered with respect to a flat plane passing via the point and tangent to the surface at that point. Whenever many parallel rays of light strike a curved or uneven reflective surface at many various points, each ray follows the law of reflection, though the reflected rays do not all appear parallel. In some situations they converge; in other situations they differ. In yet other situations the rays are scattered randomly.