Question

A lens for a 35-mm camera has a focal length given by f = 71 mm.

(a) How close to the film should the lens be placed to form a sharp image of an object that is 6.7 m away?
____mm

(b) What is the magnification of the image on the film?

Answer 1

the focal length is f = 71 mm

the object distnce do = 6700 mm

                       1/f = 1/do + 1/di

                      1/ 71 = 1/6700 + 1/di

                          di = 71.76 mm

magnification m = -di /do = - 71.76 / 6700   =- 0.01071