In this experiment designed for use with PASCO Capstone software, the Photoelectric Effect System is used to perform the photoelectric experiment, determining Planck's Constant to within 5%. This apparatus uses the conventional method of determining Planck's Constant. The metal plate in the photodiode is illuminated with various frequencies of light, selected from a mercury lamp using filters. The voltage is then adjusted to stop the photoelectric current. The stopping voltage is plotted versus the frequency, and Planck's Constant is determined from the slope of the graph.
The concept that the stopping voltage does not change with light intensity is tested using the various apertures that change the light intensity by partially blocking the light.
For the typical sample data shown, the graph of stopping voltage versus frequency gives a slope of 4.2 x 10-15 V•s. This results in a value for Planck's Constant of 6.7 x 10-34 J•s, which is 1.3% above the accepted value. Graph generated using PASCO Capstone Software.