According to the new Cartesian sign convention, the
pole (P) of the mirror is taken as origin. The principal axis is taken as
X-axis of the co-ordinate system. The sign conventions are as follows:
1.
The object is
always placed on the left of the mirror.
2.
All distances
parallel to principal axis are measured from the pole of the mirror.
3.
All the
distances measured to the right of the origin are taken as positive, while
distances measured to the left of the origin are taken as negative.
4.
Distances
measured perpendicular to and above the principal axis are taken as positive.
5.
Distances
measured perpendicular to and below the principal axis are taken as negative.
6.
Focal length of
convex mirror is positive while that of concave mirror is negative.
