Frank L. H. Wolfs
Department of Physics and Astronomy, University of Rochester, Slide 14
Einstein's Theories:
The photoelectric effect.
¥Before 1905, light was assumed to be an electromagnetic wave, characterized by an amplitude and a wavelength.
¥Most phenomena could be understood in terms of the wave nature of light.  Diffraction and interference provided compelling evidence that the wave picture of light was correct.
¥But ÉÉ the photoelectric effect (emission of electrons from metals) could not be understood in terms of the wave model of light.