Question

Why can we see our reflection on a polished metal surface or on a mirror but not on a rough surfaced stone or even on a crumbled piece of paper?

Answer 1

This is due to the smoothness of the surface on which the light is incident. There are two kinds of reflection, Specular and Diffuse. We can see the images in case of specular reflection but not in case of Diffuse reflection. I hope the below explanation and images will satisfy your question.

When light encounters a smooth surface, every reflection is perfect at each point, and light rays that were parallel before they struck the surface will be parallel after they reflect. This is known as specular reflection. Every light ray from an object gets reflected perfectly, and we can see the image of that object in the smooth surface.

Conversely, diffuse reflection occurs when light encounters a surface that is uneven. Light rays encounter the rough surface and are reflected in many directions. However, each reflecting surface is not parallel to the next. Since every light ray from the object is not reflected in parallel, the object’s light that reaches our eyes is not coherent, so we cannot see an image of it. The light is diffused and we only see the reflecting object itself, not images of other objects in its surface.