Part I: Determining the Experimental Focal Length of your Lens

1. Measure the diameter of the quarter (h_{o}) and record your measurement, in centimeters, below.

2. Position your quarter (object) and the lens so that the diameter of the quarter's image on the screen is less then 1.5 cm. Make sure that the image is brought into sharp focus.

3. Measure the distance between the object and the lens (s_{o}). Record the measurement, in centimeters, in the table below.

4. Measure the distance between the lens and the screen (s_{i}). Record the measurement, in centimeters, in the table below.

5. Use the thin lens formula

or equivalently,

,
along with your measured values for s

_{o} and s

_{i} to calculate the focal length of your lens. Show your work on this paper and record your values in the table below.

6. Repeat steps 2-5 for image heights equal to the diameter of your quarter and then for greater then 5.0 cm.