Question

can the optical centre of a lens be outside of it (it's written in my book)

Answer 1

the central point  of the lens its optical centre it is represented by the letter o
it always remain at the centre it can not be outside of the lens

Answer 2

Answer:

Yes,it can be outside of a lens.

Explanation:

If radii of the curvature have a large difference , it is possible that optical centre is outside the lens.