18 questions · 9 almanac · 0 findings

Photoelectric Effect

Light ejecting electrons from matter, and its quantum explanation.

Almanac Light Arrives in Countable Packets
  • Why did increasing the brightness of light below a certain frequency fail to eject electrons from a metal surface?
  • Why did this paper, rather than relativity or E=mc², end up winning Einstein his Nobel Prize?
Almanac Light Arrives in Packets, Not Waves
  • Why did light below a certain threshold frequency fail to eject electrons no matter how bright the lamp?
  • Why did the Nobel Committee choose the photoelectric effect over relativity to honor Einstein?
  • How did the discovery that light arrives in discrete packets make quantum mechanics unavoidable?
  • What modern technologies trace back directly to the photoelectric effect?
Almanac A Photon Recoils Like a Billiard Ball
  • What did Compton observe when X-rays scattered off a graphite target?
  • Why was the wavelength shift in scattered X-rays hard to explain using wave theory alone?
  • How does treating a photon as having momentum explain the Compton effect's wavelength shift?
  • Why did the Compton effect settle the debate over whether light behaves as a particle?
Almanac A Droplet Held Still by Argument
  • Why did Millikan spend years trying to disprove Einstein's photoelectric equation before his own measurements ended up confirming it?
Almanac A Contrail for the Invisible
  • What did Compton's X-ray scattering experiment prove about the nature of light?
  • What discredited the classical, continuous-wave picture of radiation?
Almanac He Declined to Prolong It
  • What three discoveries did Einstein publish in his 1905 annus mirabilis papers?
  • Why did Einstein's 1921 Nobel Prize cite the photoelectric effect rather than his theory of relativity?