Header image  

Advanced Physics Laboratories

       
spacer
line decor
line decor
spacer
 
 
 
spacer


Photoelectric Effect

ABOUT THE EXPERIMENT

This very elegant experiment probes the emission of electrons from the surface of a metal when illuminated by light. By carefully measuring the stopping potential as a function of wavelength of the incident light, you will show that the threshold for emission is governed not by the intensity of light but by its frequency, consistent with Planck’s concept (1900) of the quantum of energy. Einstein’s explanation of this effect in 1905 ushered in a new, quantum, description of light, as well as originating a valuable technique for chemical analysis of surfaces: photoelectron emission spectroscopy.


WHAT YOU WILL LEARN
  • Light is ...photons! The Einstein formulation of the photoelectric effect. Work functions.
  • Photocell operation. Mercury discharge lamp. Interference filters. Stopping voltage.
  • Measurement of Planck's constant!!
PREPARATION
  • Required reading:
    1. A.C. Melissinos "Experiments in Modern Physics", Ist Ed., Chapter 1.4
    2. R. Eisberg and R. Resnick, Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles, Chap. 2.1-2.3
    3. Laboratory Procedure (for older setup)
    4. Addendum for Procedure with new setup
    5. Circuit Diagram
  • Recommended reading: 
    • Serway, Moses, Moyer, Modern Physics, Sec 2.5
    • H. Haken  and H. Wolf, The Physics of Atoms and Quanta, Chapter 5.3
OTHER DOCUMENTATION