1. ## problem

An object is 2.55cm from a convex lens of 10.55cm focal length. where is the image located?

2. Originally Posted by Teck
An object is 2.55cm from a convex lens of 10.55cm focal length. where is the image located?
$\frac{1}{d_i}+\frac{1}{d_o}=\frac{1}{f}$

Here do=2.55 cm and f = 10.55 cm.

$\frac{1}{d_i}=\frac{1}{f}-\frac{1}{d_o}$

$\frac{1}{d_i}=\frac{1}{10.55}-\frac{1}{2.55} \approx -0.297370133$

$d_i \approx -3.36$cm to 3 significant digits.

Note that di is negative (so the image is on the same side as the object), as it should be since do is inside the focal length.

-Dan