Quantized light

All observable phenomena are inherently quantum events, but due to the coarseness of our senses and measuring instruments, only in some circumstances are quantum effects manifest. This first started to be realized fully by Einstein, who correctly guessed that light comes in small packets of energy called quanta.

This sequence of photographs shows that photography is a quantum process. In the fist photographs, the number of photons is very small, and they arrive on the film with a probability proportional to the brightness of the image at that point. The number of photons ranges from about 3 000 in the first exposure to about 30 000 000 in the final exposure [CREDIT: Prof. Thomas D. Rossing, Vision: Human and electronic]

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Notes

• Photoelectric effect
  • VIDEO: Photoelectric effect demo [MP4 - 15MB]
  • PhET simulation - An applet which simulates the photoelectric effect
• Ionization and excitation
• Energy levels and line spectra
• Fluorescence
• Wave–particle duality
  • Wave–particle duality slides
• Laser slides

Prep

• On the photoelectric effect
  • On the photoelectric effect answers
• On fluorescent lamps
  • On fluorescent lamps answers

Other interesting stuff

• Low-energy electron diffraction (LEED) poster
• The quantum exchange - resources for learning more about the quantum world