You are holding a lens in your hand. How can you tell if it is:
(a) positive (converging)
(b) negative (diverging), or
(c) neither (a) nor (b) above... draw pictures to show...
I will try to keep the lens on top of the newspaper and focus it so that the object falls ...
Optics of lenses are discussed. Diagrams of positive (converging), negative (diverging), or neither are given to help explain the solution.