Chapter 25, Problem 46GP

An amateur photographer purchases a vintage camera at a flea market. In order to determine the focal length of the camera's lens, he sets a soup can at various distances from the camera At each distance he brings the camera into focus on the can and then carefully measures the distance between the lens and the film. His measurements are given in the table

Can distance (cm)	Lens distance (mm)
25	118
35	104
50	95
75	89
100	87

Make a plot of the inverse lens distance as a function of the inverse can distance. Using a linear “best fit’ to the data, determine the focal length of the lens.