Question

what sign convention are used for the reflection from the spherical mirror

Answer 1

distance from pole of mirror to object is taken as -ve

PO =-u

distance from pole of mirror to Image of the object is taken as -ve
PI=-v

Answer 2

Ur answer is as follows
1. sign is taken as positive for an image
behind the mirror.
2 . sign is taken as positive above the principal axis and negative below the principal axis.


Hope it helps