Sign convention for Spherical Mirrors

Sign convention for Spherical Mirrors ( Concave and convex mirror) :

According to new Cartesian sign convention:

1. All distance are measured from the pole of the mirror as origin
2. Distance measured in the same direction as that of incident light are taken as positive.
3. Distance measured against the direction of incident light are taken as negative.
4. Distance measured upward and perpendicular to the principal axis are taken as positive.
5. Distance measured downward and perpendicular to the principal axis are taken as negative.
6. The object is always placed on the left side of mirror.
7. All the distance measured from the pole(p) of mirror to the right side will be considered positive.
8. All the distance measured from the pole (p) of mirror to the left side will be negative.

Some important conclusion for sign convention : 

1. The object distance (u) is always negative.
2. If an image is formed behind a concave mirror ( to the right side ) , the image distance (v) is positive.
3. If the image is formed in front of the mirror ( on the left side ) , then the image distance will be negative.
4. The image distance (v) for a convex mirror will be always positive.
5. The focal length of a concave mirror is considered negative.
6. The focal length of a convex Mirror is considered Positive.
7. If an image is formed above the principal axis , it's height is taken as positive.
8. If an image is formed below the principal axis , then it's height is taken as negative.
9. The height of all the virtual and Eract images is considered positive.
10. The height of all the real and inverted image is taken as negative.