Answer to Question #194496 in English for Lizzie

Question

The subject is at a distance of d = 1.8 meters from the lens. Determine the focal length of the lens if the image size is 5 times the size of the subject.

Answer 1

Magnification= image size/object size

= 5

Using the formula,

Focal length = (Object distance / ((1 / Magnification) + 1))

Focal length = (1.8 / ((1 / 5) + 1))

Focal length = 1.5 m or 1500 mm