The Discovers of Photoelectricity

• What is the photoelectric effect?

  Emission of electrons from a metal surface

  
• What causes the emission of electrons in the photoelectric effect?

  Incident radiation on a metal's surface
• What is the threshold frequency in the photoelectric effect?

  The minimum frequency for electron emission
• What happens if radiation is below the threshold frequency?

  No photoelectrons are emitted regardless of intensity
• How does intensity affect photoelectron emission?

  It affects the number of emitted photoelectrons
• How does wave theory predict energy transfer?

  Energy is transferred continuously by electromagnetic waves
• What contradiction exists between wave theory and the photoelectric effect?

  Wave theory predicts continuous energy transfer
• What happens when radiation above the threshold frequency is applied?

  Photoelectrons are immediately emitted
• What did Einstein propose about electromagnetic radiation?

  It consists of discrete quanta called photons
• What is the formula for the energy of a photon?

  E = hf
• What does 'h' represent in the photon energy formula?

  Planck's constant
• Why do photons below the threshold frequency not cause emission?

  They lack sufficient energy to energize electrons
• How does the energy of emitted photoelectrons relate to incident light frequency?

  It increases with the frequency of light
• What happens to excess energy from photons after electron emission?

  It is transferred to the kinetic energy of electrons
• What did Einstein receive for his work on the photoelectric effect?

  Nobel Prize in Physics
• What is the threshold frequency of zinc?

  $6.5 \times 10^{14} \text{ Hz}$
• Why did wave theory predict photoelectron emission at $6.3 \times 10^{14} \text{ Hz}$?


  It suggested energy would accumulate over time
• How does photon theory explain the failure of wave theory in this context?

  One photon transfers energy to one electron
• What is the energy of a photon with frequency $6.3 \times 10^{14} \text{ Hz}$?


  Insufficient to energize electrons
• What are the key points of Einstein's explanation of the photoelectric effect?

  • Electromagnetic radiation consists of photons
  • Energy of photons is given by $E =$$hf$
  • Photons transfer energy to electrons
  • Emission occurs only if photon energy exceeds threshold
  • Excess energy contributes to kinetic energy of emitted electrons
• What are the differences between wave theory and photon theory regarding energy transfer?

  Wave Theory:

  • Energy transferred continuously
  • Predicts emission with sufficient intensity over time

  
  

  Photon Theory:

  • Energy transferred in discrete packets (photons)
  • Predicts immediate emission if photon energy exceeds threshold