Question

What are the adopted rules about the sign conventions for the lenses?

Answer 1

Ans.  SIGN CONVENTIONS FOR LENSES Focal length
1. f is positive for a converging lens.
2. f is negative for a diverging lens.
Object Distance
                                 
1. p is positive, if the object is towards the left side of the lens, it is called a real object.
2. p is negative, if the object is on the night side of the lens. It is called virtual object.
Image Distance
1. q is positive for a real image made on the right side of the lens by real object.
2. q is negative for a virtual image made on the left side on the lens by real object.