Question

If the image formed by a lens for all positions of an object placed infront of it is always erect and deminished,what is the nature of this lens?If the numerical value of the power this lens is 10d what is its focul length in the cartesian system?

Answer 1

the lens is concex lens.
p=10d
10=i/f
so f=0.1cm

Answer 2

The lens would be concave lens (diverging lens)...
P=-10D
F=100/P
F=100/-10 = - 10cm......