Question

A magnifying glass is held 4.0 cm from a photograph resulting in a magnification of 3.0 times. Determine the distance of the image from the lens and the focal length of the lens

Answer 1

$d=4sm$

$K=3$

_____________

$F-?$

$f-?$

_____________

$K=f/d$

$1/F=1/d+1/f$

$f=Kd=12sm$

$1/F=1/4+1/12$

$F=3sm$