Convex and Concave Mirrors – Definition, Ray Diagrams, Formulae 2023

In Physics students often encounter the term spherical mirrors, in order to find out how light is deflected and at what angles. As many concepts and chapters are directly derived from it. And taking about spherical mirrors, there are two types, Convex and Concave. Each mirror has a different principle, and ray diagram, as well as formula, which we are going to explain in much more detail. 

What are Plane Mirror and Spherical Mirror?

Convex and Concave Mirrors - Definition, Ray Diagrams, Formulae

However, before we delve into the convex and concave mirrors, let us first talk about the basics of Plane Mirrors and Spherical Mirrors, and how they are different from each other, as well as their applications. 

Plane Mirror

It is a mirror that has a flat and smooth surface, which in turn always forms a virtual form of the object, with exact shape and size, when it reflects.  Commonly, these are the mirrors people generally use in dressing rooms or makeup tables.  

Spherical Mirror

Unlike plane mirrors, spherical mirrors have a radius if curvature with a consisting curve, which results in the formation of an image, that can be either virtual or real. And more importantly, there are two types of spherical mirrors, Concave and Convex. 

What is a Concave Mirror?

A Spherical Mirror that has a reflective surface inside, is called the converging mirror. The main attribute of the concave mirror is that it focuses on pointing the light from the source falling on it, into a single point. And generally, the image formed by these types of mirrors usually varies based on the size, shape, and position of the object.  

Characteristics of Concave Mirror

  • The image formed by the concave mirror is either real or virtual and also can be small and large based on the position of the sources, and the reflecting point. 
  • For example, if the distance of the object from the source is large, then it results in real and inverted images. Whereas for the objects placed close to the source, the images formed are erect and virtual. 
  • Moreover, in this mirror, the light converges at a single point before reflecting back, which is referred to as a converging mirror. 

Ray Diagram of Concave Mirror

  • Object is at Kept at Infinity: When the parallel rays meet or converge at the Principal Focus, F. So, when the object is kept at infinity, the image will form here at the F. The image formed by this ray diagram is a point-sized, highly diminished, inverted, and real image. 

Ray Diagram of Concave Mirror

  • Object is placed at infinity and Centre of Curvature: Only diminished images are formed that are either real or inverted. 
  • Object at Centre of Curvature(C): The image of the same size is formed, that is inverted or real. 

Object between Principal Focus and Centre of Curvature 

  • Object at Principal Focus(F): A highly enlarged image, that is inverted and real. 
  • Object between Principal Focus(F) and Pole(P): Similarly enlarged is formed. 

What is a Convex Mirror?

Convex Mirror is another type of spherical mirror that has a reflective surface towards the outside of the bulge, and it is also referred to as diverging mirror. Unlike convex mirrors, the light falling on the object diverges as it reflects through the mirror. And generally, as the distance between the source and the object decreases, the size of the image formed increases. 

Characteristics of Convex Mirror

  • Through this mirror, the light diverges as it strikes the reflecting surface. 
  • The Convex mirrors always result in diminished, erect, and virtual images, regardless of the distance between the mirror and the object. 

Ray Diagram of Convex Mirror

  • Object at Infinity: A point-sized image is generally formed at the principal focus behind the convex mirror.  

Ray Diagram of Convex Mirror

  • Object is kept between Infinity and Pole: If the object is placed in between the pole and infinity of a convex mirror, a diminished, erect, and virtual image at the pole is located in mid-point, focus, and pole. 

Ray Diagram of Convex Mirror When object

Difference Between Concave and Convex Mirror


Mirror Type  Concave  Convex 
Description  The Inner Side of the mirror is reflecting, converging mirror  The Outer side of the mirror is reflecting, diverging the mirror 
Image Formed  Both Inverted, Real and Virtual, Erect images are formed  Only Virtual and Erect images are formed 
Size of Image  Depending on the distance of the object, the size of the image varies  The size of the image is smaller compared to the size of the object 
Position of the Image  Directly depends on the Position of the Object.  Does not depend on the Position of the Object, as the image is always formed within Focus. 



Here in the above article, we have provided a comprehensive description of both Concave and Convex Mirrors, along with Ray Diagrams, and Differences. And as you know, many topics like this in Physics are often complex, and the students often end up struggling to understand these topics and subjects. So, for this process, it is better to join an online coaching platform, that offers various amazing features for the students. One such online tutoring platform is Tutoroot, which offers online interactive classes for students at Budget Friendly Prices. To learn more, visit the Official Platform. 

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