Question

You wish to fom an enlarge image of an illuminated slide on a screen that is 0.55m from the slide.how far from the slide should you place a converging lens, with a focal length of 11cm in order to accomplish this?

Answer 1

We can find the object distance from the lens from the thin lens equation:

$$\dfrac{1}{d_0}+\dfrac{1}{d_i}=\dfrac{1}{f},$$ $$d_0=\dfrac{1}{\dfrac{1}{f}-\dfrac{1}{d_i}},$$ $$d_0=\dfrac{1}{\dfrac{1}{0.11\ m}-\dfrac{1}{0.55\ m}}=0.137\ m.$$

Answer:

$d_0=0.137\ m.$