Goal:
    Finding the focal length of a double convex thin lens

Equipment List:
    Pasco geometrical optics kit with optics bench and light source
    equipment holders (i.e., magnetic, holding brakets attaching the optical elements to the bench so that they can slide)
    tensor lamps

Procedure:
    Find the slide that has a circle and an arrow on it; this will be your "object". Attach this slide to the light box using the magnetic strips on the slide.
    Find the l27 mm lens. Attach it to a lens slide and set the lens slide on the optics bench.
    Find the white image screen slide and attach it to another lens slide.

Data:
    Move the lens and image slide until an image focuses on the image screen (may require patience).
    Record the image and object distances.
    Move the lens and image screen to new positions and get the image of the object in focus on the screen. Repeat this for a total of ten pairs of image and object distances.

Calculations:
Using the thin lens equation, calculate ten focal lengths corresponding to the ten pairs of data collected as described above.
Using statistics, calculate the best value of the focal length and its uncertainty.
Calculate a percent discrepancy between the accepted value and your value.
 

Analysis:
Does the value printed on the lens agree with your calculated value?
Is your discrepancy less than three percent? If so, you must be doing something right.