Experiment 13
THE CONVERGING LENS

PRELAB


PURPOSE

To study the refractive properties of a converging lens and verify the thin lens formulas.

EQUIPMENT  Pasco optical bench, light source, viewing screen, crossed-arrow target, 75 mm focal length lens.

RELEVANT EQUATIONS

Thin lens equation
Magnification

DISCUSSION

In principle, the law of refraction combined with some ray tracing techniques is all that you need to determine the location and size of images produced by a lens. However, this is quite tedious and another, more easily used, technique is valuable. This is the "thin lens" approximation and is discussed in your textbook. The symbols vary from textbook to textbook, so, if the notation in this experiment does not agree with your classroom notes, you should rewrite all equations into a consistent set.

The thin lens equation that you will verify in this experiment is , where do is the distance from the lens to the location of the object and is called the object distance. The quantity di is the distance from the lens to the location of the image and is called the image distance. The quantity f is the focal length of the lens.

The magnification m of the image is determined by .

The sign conventions that go along with these equations are discussed in your textbook. Please consult it for details.


Print out and complete the Prelab questions.