The focal length of a convex lens by graphical method

Content of this page :

1.    Introduction of the experiment.

2.    Aim of the experiment.

3.    Tools of the experiment.

4.  Steps and methods of the experiment.

5.    Parameter, Theory and Final law of the experiment.

6.    Medical application and advantages of the experiment.

1. Introduction of the experiment:

The Focal length Is the distance between center of the lens and the focal point of the lens. This point produce from the meeting of parallel rays of light . A lens is a transparent curved surface that is used to refract light. It is usually made from glass. There are two different types of lenses

2. Aim of the experiment:

Determination the focal length of the convex lens by graphical method

3-Tools of The experiment

·         Convex lens

·         Meter scale

·         Source of light ( lamp )

·         White screen

·         Object

·         Two holders for lens and object



4. Steps and methods of the experiment:

1-Place the object pin between the lamp and the lens .

2-Move the lens away from the object slowly to the place where the sharpest image is formed on the screen , record the distance between the object and lens and the distance between lens and the screen .

3-Increase the distance of the object (3cm) and move the lens until the sharp image formed on the screen record the distance of object and image

4-Repeat step 3 at least 5 times, every time you should change the position of the screen and move the lens until the formation of the sharp image.



5-ParametersFinal Law of The experiment


U: Distance of object from lens (cm)

V: Distance of image from lens V (cm)

F: the focal length of the convex lens


Final Law:

The focal length of lens is


6-Table of The readings:

7-Medical application

1-To diagnose and treat eye defects such as long sight and short sight.

2-To diagnose and treat the Astigmatism.

3-It is used in medical and biological devices like microscopeendoscope.



microscope, research, lab-385364.jpg

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