1. Wave-Particle Duality

  1. Proposed to explain the dual nature of light and electromagnetic radiation.
  2. Light exhibits both wave-like and particle-like properties.
  3. Wave nature: Demonstrated by interference and diffraction.
  4. Particle nature: Demonstrated by the photoelectric effect.

2. Photoelectric Effect

  1. Discovered by Heinrich Hertz and later explained by Albert Einstein.
  2. When light strikes a metal surface, it ejects electrons from the surface.
  3. Ejected electrons are called photoelectrons.
  4. Occurs only when the light has a minimum frequency (threshold frequency).
  5. Einstein's explanation used the concept of photons, or light quanta.
  6. The kinetic energy of the photoelectrons depends on the frequency of light, not its intensity.
  7. Forms the basis of many devices, such as photoelectric cells and solar panels.

3. Photons

  1. A photon is a quantum of electromagnetic radiation.
  2. Photons are massless particles and always travel at the speed of light in a vacuum.
  3. The energy of a photon is given by the formula: E = hν, where h is Planck’s constant and ν is the frequency of light.
  4. The momentum of a photon is given by p = E/c, where c is the speed of light.
  5. Photons are responsible for interactions in electromagnetic phenomena.

4. Planck’s Hypothesis

  1. Proposed by Max Planck to explain blackbody radiation.
  2. States that energy is emitted or absorbed in discrete quanta or packets.
  3. The energy of each quantum is directly proportional to its frequency.
  4. Formula: E = hν, where h is Planck’s constant (6.626 × 10⁻³⁴ Js).
  5. Revolutionized the understanding of energy and quantum mechanics.

5. Applications

  1. Used in photovoltaic cells to convert sunlight into electricity.
  2. Forms the basis of quantum theory and modern physics.
  3. Photoelectric effect is critical in digital imaging and optical sensors.
  4. Helps in understanding phenomena like Compton scattering and electron microscopy.

6. Key Takeaways

  1. Wave-particle duality bridges the classical and quantum views of light.
  2. The photoelectric effect validated the particle nature of light.
  3. Planck’s hypothesis laid the foundation for quantum mechanics.
  4. Photons are central to understanding light-matter interaction.

Category

Questions

  1. What is the minimum energy required to remove an electron from a metal surface called?
  2. What is the main application of the photoelectric effect?
  3. What is the role of photons in the photoelectric effect?
  4. How does increasing the stopping potential affect the photoelectric current?
  5. What does the threshold frequency depend on?
  6. What is the maximum kinetic energy of an ejected electron in the photoelectric effect?
  7. What type of surface is best for observing the photoelectric effect?
  8. What is the relationship between frequency and wavelength?
  9. What happens to the kinetic energy of electrons if the frequency of light increases above the threshold?
  10. What does the photoelectric effect prove about light?
  11. What happens to the photoelectric effect if the intensity of light increases but frequency remains constant?
  12. Which constant is used in the formula E = hν?
  13. What is the relationship between photon energy and wavelength?
  14. What is the stopping potential in the photoelectric effect?
  15. What is the significance of Planck’s hypothesis?
  16. What is the term for light being absorbed in discrete packets?
  17. Which property of light supports the wave-particle duality?
  18. What determines the number of electrons ejected in the photoelectric effect?
  19. What is Planck’s constant approximately equal to?
  20. What happens to the photoelectric current when the intensity of light increases?
  21. What is the work function of a material?
  22. What happens if the frequency of light is below the threshold frequency in the photoelectric effect?
  23. Which formula represents the energy of a photon?
  24. What is the energy of a photon directly proportional to?
  25. Who explained the photoelectric effect using the quantum theory?
  26. What is the threshold frequency in the photoelectric effect?
  27. What determines the kinetic energy of the emitted electrons in the photoelectric effect?
  28. Which particle is responsible for the photoelectric effect?
  29. What is the phenomenon where light behaves as particles?
  30. What is emitted during the photoelectric effect?
  31. What is the unit of Planck’s constant?
  32. Who proposed the quantum theory of radiation?
  33. What happens to photon energy as frequency increases?
  34. Which device uses the principle of the photoelectric effect?
  35. What is the effect of increasing light frequency in the photoelectric effect?
  36. What proves the particle nature of light?
  37. What does the term "quantum" refer to in the photoelectric effect?
  38. What is the relation between photon energy (E) and Planck’s constant (h)?