Answer to Question #57703 in Optics for dabas

Question

How is focal length related to converging power of a convex lens?

Answer 1

The most important characteristic of a lens is its principal focal length, or its inverse which is called the lens strength or lens "power".
So, the focal length of a convex lens (in meters) is the inverse of converging power of the lens (in diopters):
f=1/P.