Formative Notes on Image Formation by Light Rays and Mirrors

Fundamentals of Image Formation by Light Rays

Image formation by optical systems depends on how light rays interact with reflective surfaces and are processed by human perception or projected in physical space. When light bounces off an object, such as the human body, it travels in rays toward a mirror. The direction and behavior of these reflected light rays determine whether the resulting image is classified as a virtual image or a real image.

Characteristics of Virtual and Real Images

A virtual image is formed when light bounces off an object, hits a mirror, and then bounces off the surface of the mirror in a diverging pattern. The human brain interprets light as traveling in continuous straight lines, extrapolating these diverging rays backward behind the mirror plane. This tricks the brain into seeing a "fake" image that appears to be located inside or behind the glass. Virtual images are upright relative to the object and cannot be projected onto a screen because the light rays do not physically intersect behind the mirror.

A real image is formed when light rays bounce out from an object and converge (intersect) at a specific physical point in mid-air after reflecting off a mirror surface. Because the light rays physically intersect at that exact spot, a real image is produced. A defining visual characteristic of a real image is that it is created upside-down relative to the original object. Real images can be caught or projected onto a physical screen placed at the exact point of intersection in space.

Mirror Classifications and Image Capabilities

Mirrors are categorized according to the curvature of their reflective surfaces, which dictates the types of images they are capable of forming:

Plane mirrors possess a flat reflecting surface. These mirrors can only produce virtual images, which appear upright and behind the plane of the mirror surface.

Convex mirrors possess a reflecting surface that is curved outwards toward the incoming light. These mirrors can only produce virtual images because the reflected light rays always diverge away from each other.

Concave mirrors possess a reflecting surface that is curved inwards away from the incoming light. Because of their inward curvature, concave mirrors can produce both real images and virtual images, depending on the relative distance between the object and the mirror.