Photoelectric facts
Stories from Physics
for 11-14
14-16
16-19
- In his 1905 photoelectric paper, Einstein did not use the term photon, but referred to a ‘light quantum’. The word photon was first used in 1926 by the chemist Gilbert Lewis who is best known for the discovery of the covalent bond.
- The way that the photoelectric equation (eV=hv-Φ) is presented in textbooks is “at best, misleading, and at worst, simply incorrect”, according to physicist Stephen Klassen. He argues that when the photoelectric effect is investigated at room temperature, the electrons in the metal surface have a distribution of energies and hence there is no single value of the stopping potential. It is therefore impossible to calculate the stopping potential at room temperature using the linear equation.
- It has been observed that the cuticle of the Oriental hornet displays photoelectric properties. Potential differences of 60 - 180 mV were detected between the tips of an Oriental hornet’s body with the highest values occurring at noon due to peak irradiation with ultraviolet radiation. The evolutionary purpose of the effect is not known.
- William Henry Bragg, who won the Nobel Prize for his work with his son Lawrence on X-ray crystallography, nicely described the incredulity of scientists when they first made sense of the dual nature of light:
On Mondays, Wednesdays and Fridays light behaves like waves, on Tuesdays, Thursdays and Saturdays like particles, and like nothing on Sundays.
References
Photoelectric facts
S. Klassen, The photoelectric effect: Reconstructing the story for the physics classroom, Science & Education, vol. 20, no. 7, 2011, pp. 719-731, p. 721
R. G. Keesing, The measurement of Planck's constant using the visible photoelectric effect. European Journal of Physics, vol. 2, no. 3, 1981, pp. 139.-149
J. S. Ishay, T. Benshalom-Shimony, A. Ben-Shalom, & N. Kristianpoller, Photovoltaic effects in the oriental hornet, Vespa orientalis. Journal of Insect Physiology, vol. 38, no. 1, 1992, pp. 37-48.
A. Sverdlov, & J. S. Ishay, J. S. (2004). Photovoltaic Effects in Hornets Are Correlated with the Time of Day. Photochemistry and Photobiology, vol. 79, no. 6, 2004, pp. 510-515.
F. Ashall, Remarkable Discoveries! Cambridge, Cambridge University Press, 1994, p. 57
