Question

Consider an object with do=12cmdo=12cm that produces an image with di=15cmdi=15cm. Note that whenever you are working with a physical object, the object distance will be positive (in multiple optics setups, you will encounter "objects" that are actually images, but that is not a possibility in this problem). A positive image distance means that the image is formed on the side of the lens from which the light emerges.

Part A

Find the focal length of the lens that produces the image described in the problem introduction using the thin lens equation.

Answer 1

Using lens formula, For the Real image,

Using the lens formula, For the Virtual image,

Solving,

So we have two Focal length over here,

For Real image

f = 6.67cm

And for Virtual image,

f = 60 cm