TEACHERSí NOTES FOR
THE PHOTOELECTRIC EFFECT
VIRTUAL LAB

 
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NOTES FROM VARIOUS REFERENCES

A. "Physics for Poets," Robert March, McGraw-Hill, 1970, pages 191-194:

  1. The effect is easy to do with blue light, but not with red light.
  2. Rate of liberated electrons (number/second) is proportional to brightness (intensity).
  3. Energies of electrons are independent of brightness, but dependent upon frequency.
  4. "More photons meant more electrons, but not faster ones . . ."
  5. Einstein coins name "photons." Energy absorbed by an electron is the energy of a single photon (which, by Planck, is equal to hf).
  6. Slope of KE vs. F graph will equal h. Various metals will have different x (and y) intercepts but theyíll have the same slope.
B. "Seven Ideas that Shook the Universe," N. Speilberg and B.D. Anderson, 2nd edition, J. Wiley and sons, 1995, pages 263-272:
  1. Photoelectric effect first recognized by H. Hertz in 1887. Electrons liberated by photons are often called "photoelectrons." They show a voltage source (battery) in their picture, though that it is only used for determining the energy of the liberated electrons. It is not strictly necessary to observe the effect, only to measure energies of the electrons. (Page 270)
  2. Interestingly, Einstein called his explanation a "heuristic" one (at least at first). (Page 271)

 
  C. "Non-Classical Physics," Randy Harris, Addison-Wesley, 1998, pages 71-96:
  Page 72 has an interesting and useful table:

 
Element Work Function (eV) Work Function (J.) Min. Freq. (Hz)
Potassium 2.2 3.52 x 10 ?19 5.33 x 10 14
Sodium 2.3 3.68 x 10 ?19 5.58 x 10 14
Magnesium 3.7 5.92 x 10 ?19 8.96 x 10 14
Zinc 4.3 6.88 x 10 ?19 1.04 x 10 15
Chromium 4.4 7.04 x 10 ?19 1.07 x 10 15
Tungstate 4.5 7.20 x 10 ?19 1.09 x 10 15