The Photoelectric Effect System uses the conventional method to determine Planck’s Constant within 5%. First, the metal plate in the photodiode is illuminated by various light frequencies; selected from a mercury lamp with filters. Then, the voltage is adjusted to stop the photoelectric current. The stopping voltage is then plotted against the frequency, and Planck’s Constant is determined using the slope. Students can test whether the stopping voltage changes with light intensity using the various apertures and corresponding light intensities.
How it Works: The filters and the apertures are built into the front of the photodiode case, making it easy to clean and eliminating the need for a separate storage box. To change the aperture size, simply pull outward on the aperture ring and rotate it to a different aperture. The filter wheel rotates independently of the aperture ring to select different frequencies of light. The wheel clicks into place, assuring that the filter is aligned with the aperture.