Walker, Kameron
Physics 002, Sec 03
Focal Length of Lenses
Objective: The purpose of the experiment is to measure the focal length of convex and concave
lenses.
Theory: Lenses may be mathematically represented by
Equation 1: (1/o)+ (l/i)=(l/f)
This applies for both concave and convex lenses, as well as for real and virtual images.
“O” represents object-to-lens distance. “I” is image-to-lens distance. “F” is the focal length of a
lens. Magnification, M, is mathematically represented as
Equation 2: hi/ho=i/o
“H” is the size, applied to the image and the object respectfully.
Hypothesis: If we can determine the distances between object, image, and light source, we can
determine the focal length and confirm with magnification.
Apparatus: optical bench, lens holders, screen, illuminated object (lamp) convex lenses,
concave lenses.
