Question

Down to one try left on this hw problem, please help!

A lens for a 35-mm camera has a focal length given by f = 65 mm.

(a) How close to the film should the lens be placed to form a sharp image of an object that is 6.2 m away?

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

Answer 1

aplly the formula for focal length as

1/f = 1/u +1/v

so

here u   is object distance = ?

v is image distance = 6.2 m

focal length f = 0.065 m

so

1/u = 1/f -1/v

u = vf/(v-f)

u = 6.2 * 0.065/(62-0.065)

u = 6.5 mm

------------------

magnification m = -v/u

m   = 6.2/0.0065

m = 952.84