Rules for Drawing Ray Diagrams in Mirrors
Rule - 1
Ray parallel to principal axis will pass through focus after reflection.
For Concave Mirror we see that light rays pass through focus after reflection.
In Convex Mirror focus is positioned on right side of the mirror, so it appears that rays passes through focus after reflection.
Rule - 2
Ray passing through focus will become parallel to Principal Axis after Reflection
In Concave Mirror rays coming from focus become parallel to Principal Axis after reflection.
In Convex Mirror, it appears that rays passing through focus become parallel to Principal Axis after reflection.
Rule - 3
Ray passing through Center of Curvature will follow the same path back after Reflection
In Convex Mirror ray passing through Center of Curvature follow the same path back after reflection.
In Concave Mirror it appears that the ray is passing through the Centre of Curvature and then it comes back to its path after reflection.
Rule - 4
Ray incident at Pole is reflected back making same angle with Principal Axis
As shown in figure below, Angle of Incidence (i) = Angle of Reflection (r) for Concave and Convex Mirror.