Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.
Characteristics of the image obtained by a concave mirror
There are five cases through which one can understand the characteristics of the image obtained by a concave mirror and they are as follows:
Object placement | Image obtained | Image characteristics |
When the object is placed at infinity | The image obtained is at the focal point | Image is a point |
When the object is moved from infinity to the centre of curvature | Image move from focal point to centre of curvature | The size of the image is increased, real, and inverted |
When the object is at the centre of curvature | The image obtained is at the centre of the curvature | The size of the image remains the same, real, and inverted |
When the object moves from centre of curvature to focal point | Image move from centre of curvature to infinity | The size of the image is bigger than the object, real, and inverted |
When the object is at the focal point | The image is at infinity | Infinitely big |
When the object moves from the focal point to mirror | Image move from minus infinity to mirror | The size of the image decreases, larger than the object, virtual, and upright |
Check out the video given below to know more about spherical mirror

Related Questions:
Veary nice class
Very nice class
To good
Wow
Its too good