Image Formation in Convex Mirror

Last Updated : 14 Jan, 2024

Convex Mirror also called Diverging Mirror is a curved reflective surface that bulges outward. The image formed by a convex mirror is always erect, virtual, and diminished in size. The image formed by a convex mirror is generally formed behind the mirror.

In this article, we will understand the meaning and definition of a convex mirror, the various characteristics, applications, and related terms of a convex mirror, and the difference between a convex and a concave mirror.

What is a Convex Mirror?

A convex mirror is a round mirror that curves outward. The surface of the mirror bulges or sticks out, facing the light source. It’s also called a diverging mirror because it makes the light spread out instead of coming together.

Properties of Convex Mirror

These mirrors don’t work for focusing light, but they follow the rules of reflection. Each point on the mirror follows these rules, and the normal (a line drawn perpendicular to the mirror’s surface) connects the center of curvature to the point where light hits.

Convex mirrors make virtual images, so they can’t project them onto a screen. The focal point and center of curvature are imaginary, so the image forms inside the mirror. While looking at the image from far away, it seems smaller than the real object, but it gets bigger as the object comes closer to the mirror.

Concave and Convex Mirrors

Learn more about, Concave and Convex Mirrors

Ray Diagrams of Convex Mirror

In a convex mirror which has an outward curve, when light rays come parallel to each other and hit the mirror, they reflect away.

How to Make a Ray Diagram of Convex Mirror?

Parallel Rays: Start with two rays coming in parallel. Picture them like arrows pointing to the mirror.

Reflection: The rays reflect off the mirror surface. Instead of coming together like they would in a concave mirror, they spread out.

Diverging Rays: After reflection, the rays move apart. If you extend these reflected rays backward, they appear to come from a point behind the mirror.

Virtual Focus Point: This imaginary point where the rays seem to meet is called the “virtual focus point” for a convex mirror.

Object at Infinity

When an object is positioned at infinity in front of a convex mirror, parallel rays reflecting off the mirror appear to converge at an imaginary point behind the mirror. This point is not a real focus but is created by extending the reflected rays backward. As a result, the virtual image formed is diminished, upright, and located behind the mirror.

Image Formation When an Object Is Placed between Infinity and the Pole.

Object at Infinity

Object at a Finite Distance

In the scenario where the object is placed at a finite distance from a convex mirror, we examine two distinct rays originating from the object.

One ray moves parallel to the principal axis, while the other is directed toward the center of curvature of the mirror.
After reflecting off the mirror surface, these rays converge to form an image.
This image is situated behind the mirror, between the pole (P) and the focus (F). The characteristics of this image include being smaller in size, virtual, and upright.

Image Formation When an Object Is Placed between Infinity and the Pole

When an object is positioned between infinity and the pole of a convex mirror, we observe the formation of an image using two specific rays. One ray is parallel to the principal axis, and the other is directed towards the center of curvature of the mirror. Following reflection, these rays come together to create an image located between the pole (P) and the focus (F) behind the mirror. This resulting image is smaller, appears behind the mirror, and is upright, but it is virtual in nature.

Object Is Placed between Infinity and the Pole