Compund Microscope Construction 02/02/08

Today in class we learned more about focal points and how light reflect off of certain surfaces like mirrors. When light is reflected off of more than one surface or mirror it is called compound. A compound microscope has two or more lenses that reflect light. A simple diagram of a compound microscope can be seen below:



Additionally, In class we actually built a compound microscope. We had to work in our groups to find a way to create a compound microscope with two lenses. One lens had a magnification of 10X. In order to setup the microscope we first had to find the focal length of one of the lenses.

In order to help find the focal length we were given the following equitation:

1/F = 1/do + 1/di
Object distance (do), the image distance (di), and the focal length (f).

Our group used two different methods to find the focal point of the lens. First, we looked at a object through the lens. We then moved the object backward until the image became inverted. This method however only gave us one of the variables for the equation.

The second method that we used was to shine a light source through the lens. The distance from the lens to the light source we called do. We then put a white board in front of the lens. We measured the distance from the white board to the lens at the point which the light source on the white board became focused. We called this value di. With these two quantities we were able to solve for F, or the Focal length.

Knowing the focal point of one of the lenses gave us the ability to construct a compound microscope with the 10X lese. A picture of our microscope can be seen below: