Reflection of Light — Important Questions

Virtual, Erect, Same size as object, Laterally inverted

A plane mirror forms an image that is virtual (cannot be obtained on screen), erect (upright), same size as the object, and laterally inverted (left appears right). The image is not real as it cannot be projected on a screen.

f = R/2

For any spherical mirror (concave or convex), the focal length is half of the radius of curvature, i.e., f = R/2. This is a fundamental relationship in spherical mirror geometry.

Convex mirror

A convex mirror always forms a virtual, erect, and diminished image regardless of the object's position. Concave mirrors can form different types of images depending on object position.

At infinity

When an object is placed at the focus of a concave mirror, the reflected rays become parallel and the image is formed at infinity. This principle is used in torches and headlights.