Image Formation by Concave Mirror

A concave mirror is a curved mirror with an inward-curved reflecting surface. It can form different types of images, depending on the object's position relative to the mirror. There are two main cases: a real image and a virtual image.

Real Image

A real image is an image formed when actual light rays converge at a point in space. It can be projected onto a screen, making it visible. A real image is formed under specific conditions when the object is located beyond the focal point of the concave mirror.

Key Concepts

Focal Point (F)

The focal point is a point on the principal axis of the mirror where parallel rays of light either converge (in the case of a concave mirror) or appear to diverge (in the case of a convex mirror) after reflection. It is denoted as "F."

Focal Length (f)

The focal length of a mirror is the distance between the mirror's surface and its focal point. It is half of the radius of curvature (R) of the mirror.

Center of Curvature (C)

The center of curvature is the center of the sphere of which the mirror's curved surface is a part. It is located on the principal axis, and the mirror's radius of curvature is the distance from the mirror's surface to the center of curvature (R=2f).

Image Formation

for Real Image

When an object is placed beyond the focal point (F) of a concave mirror (i.e., the object is farther away from the mirror than the focal length), a real, inverted, and diminished image is formed on the same side of the mirror as the object.

for Virtual Image

A virtual image is an image formed when extended light rays appear to diverge from a point, but they do not actually converge at that point. It cannot be projected onto a screen and is not "real" in the sense of forming a physical image.

Image Formation for Virtual Image

When an object is placed between the focal point (F) and the mirror's surface (closer to the mirror than the focal length), a virtual, upright, and magnified image is formed on the same side of the mirror as the object. The image is virtual because the light rays do not actually converge; they only appear to diverge from a virtual point behind the mirror.

In Summary

A concave mirror can form both real and virtual images depending on the object's position relative to the mirror. Understanding the concepts of focal point, focal length, and center of curvature is crucial for determining the type and characteristics of the image formed by the mirror. The mathematics involved in these calculations can be more complex, but for a basic understanding, it's essential to grasp the fundamental principles of image formation.