In order to draw a ray diagram for a concave mirror follow the steps given below:

- Draw a circular arc XY with the help of a compass.
- Mark C for the point at which a compass needle stands.
- Locate the middle point P of the mirror XY.
- Draw a straight line p[assign through P and C.
- Shade the outer surface of XY.
- Locate the mid-point of CP and let it be F.
- Place an object at the required point, i.e., place the object AB beyond C as shown in the figure.
- Follow the rules mentioned below.
- Draw a straight line AM parallel to the principal axis.
- Draw a straight line passing through M and F.
- Draw another straight line passing through A and F and produce it to the point N in XY. AN is an incident ray passing through the focus hence it reflects parallel to PC. Draw a straight line parallel to PC which intersects MF at A'.
- Draw A'B' perpendicular to the principal axis. Here A'B' is the image of AB.
- Measure the size and position of A'B'

The image formed is diminished, inverted, and real which lies between the focus (F) and center of curvature (C).