# Experiment7

Topics: Optics, Focal length, Lens Pages: 7 (1697 words) Published: April 13, 2013
EXPERIMENT 7

EXPERIMENT 7

EXP 7: THE FOCAL LENGTH OF A CONVEX LENS BY GRAPHICAL METHOD EXP 7: THE FOCAL LENGTH OF A CONVEX LENS BY GRAPHICAL METHOD

ABSTRACT

The report is about the focal length of a convex lens using the graphical method. The aim of the report is to determine the focal length of a convex lens using the graphical method. The focal length of an optical system is a measure of how strongly the system converges or diverges light. The method that was used was experimentation because it is one of the fundamental steps in the scientific method. In addition experimentation is a methodical trial and error procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Furthermore experimentation was used because it is testable and replicable such that a different person can perform the same experiment and get the same results. In the experiment the focal length was first approximated to obtain a rough value of 10cm, and through experimentation it was found out that the value was obtained for the focal length of the convex lens was 9.08± 0.3cm. The method used for the experiment is the best method as it is accurate because people can follow the same procedure and get the same results. It was concluded that the focal length of a convex lens is 9.8 ± 0.3cm.
Table of Contents
INTRODUCTION4
MATERIALS AND METHODS5
RESULTS AND ANALYSIS7
DISCUSSION11
CONCLUSION11
REFERENCES11

INTRODUCTION
The report is about determining the focal length of a convex lens using the graphical method. According to research the focal length of an optical system is a measure of how strongly the system converge light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length; that is, it bends the rays more strongly, bringing them to a focus in a shorter distance. Furthermore research states that when light rays enter a piece of glass, they refract, or bend, because the speed at which they are travelling changes. If the glass is shaped certain ways, the image that results from the light's passage can appear larger, smaller, closer, or farther away than the original object. Magnifying glasses, eyeglasses, cameras, and microscopes are a few of the instruments that use lenses. The human eye is another example. In addition research a convex lens is one that is thicker at the middle than the ends and converges light so it meets at a single point. The principal axis is the line that joins the centres of curvature of its surfaces. The focal point is the point where a beam of light parallel to the principal axis converges. The focal length is the distance from the centre of the lens to the focal point. The purpose of the experiment carried out was to determine the focal length of a convex lens using the graphical method. The focal length was determined using the graphical method. The graphical method was used because it more accurate compared to calculations as it caters for the errors done by the person carrying out the experiment. In order to determine the focal length a rough value was obtained and if the results are close to the rough value it shall be concluded that the findings are accurate. If there is a huge difference between the results and the rough value it shall be concluded that the findings are not accurate.

METHODS AND MATERIALS
The materials used in the experiment were as follows;
APPARATUS:
* Convex lens and holder
* Optical bench
* Light source and support
* Object (wire gauze in a circular...

Please join StudyMode to read the full document