1. The Particle Nature of Light

2. Key Concepts… Experimental: Theoretical Black body radiation curve
Discovery of Photoelectric Effect (Hertz, Lenard, Millikan)
Compton Scattering
Theoretical
Planck quantization of energy
Einstein extends Planck’s ideas to the “quantum” of light or photon

3. Photoelectric Effect is Critical
Millikan’s brilliant (albeit reluctant) confirmation of Einstein’s quantum hypothesis
Shows that light behaves in a very “non-classical” way
go to kcvs.ca applet of this

4. Photon reveals light’s “particle nature”
Light has both wave and particle nature but is neither
Photon is an example of the strange quantum idea we will also call “quanton”
First glimpse of the wave-particle duality that lies at the heart of quantum physics

5. Compton Scattering…
The scattering of x-ray photons by electrons provides compelling evidence for the photon idea
go to kcvs.ca applet

6. Sample questions…
Q3T.1, T4
Q3B.4
Q3S.1
Q3S.3
Q3S.7