Focal Length Of A Concave Mirror

Name: Gihan Mallawaarachchi Date: 19/02/02

Aim: To observe the focal length of a concave mirror.

Materials:

Procedure:

An approximate focal length was found using parallel light from a distant object.
The mirror was placed in a stand. Pin (A) was moved in its stand, in front of the mirror till there was no parallax between the pin and its inverted image.
The distance from the object to the mirror was measured.
The object pin was placed between F and C. Then the second pin (B) was moved about till there was no parallax between (B) and the image (A). The distances of the image and objects were measured.
Step 4 was repeated for another position of (A).
The image of a light source was located using a screen. Then the image and object distances were measured.
Step 6 was repeated twice.
The corresponding values of u and v were tabulated.

Results:

Data Analysis:

The tabulated results of step 8 illustrated the image distance, and the object distance .

Graphical method

The two variables, and were substituted into the linear equation y = mx + c to form = - + .
The data was plotted on the graph versus , thus proving the relationship between the variables and the linear equation.