1. Classical Physics Newton’s laws: Newton’s laws: allow prediction of precise trajectory for particles, with precise locations and precise energy at every instant. allow prediction of precise trajectory for particles, with precise locations and precise energy at every instant. allow translational, rotational, and vibrational modes of motion to be excited to any energy by controlling applied forces. allow translational, rotational, and vibrational modes of motion to be excited to any energy by controlling applied forces.

2. Wavelength ( ) - distance between identical points on successive waves. Amplitude - vertical distance from the midline of a wave to the peak or trough. Fig 8.1 Characteristics of electromagnetic waves

3. Properties of Waves Frequency ( ) - the number of waves that pass through a particular point in 1 second (Hz = 1 cycle/s).

4. Maxwell (1873) proposed that visible light consists of electromagnetic waves. Electromagnetic radiation - emission and transmission of energy in the form of electromagnetic waves. Speed of light (c) in vacuum = 3.00 x 10 8 m/s All electromagnetic radiation:

5. Figure 8.2 The Electromagnetic Spectrum R O Y G B I V

7. “Mysteries” of classical physics Phenomena that can’t be explained classically: 1.Blackbody radiation 2.Atomic and molecular spectra 3.Photoelectric effect

8. Fig 8.4 Experimental representation of a black-body Capable of absorbing & emitting all frequencies uniformly

9. Fig 8.3 The energy distribution in a black-body cavity at several temperatures Stefan-Boltzmann law: E = aT 4 E

10. Fig 8.5 The electromagnetic vacuum supports oscillations of the electromagnetic field. Rayleigh - For each oscillator: E = kT Rayleigh – Jeans law: d E = ρ dλ where:

11. Fig 8.6 Rayleigh-Jeans predicts infinite energy density at short wavelengths: d E = “Ultraviolet catastrophe”

12. Fig 8.7 The Planck distribution accounts for experimentally determined distribution of radiation. d E = ρ dλ Planck: Energies of the oscillators are quantized.

13. Fig 8.10 Typical atomic spectrum: Portion of emission spectrum of iron Most compelling evidence for quantization of energy

14. Fig 8.11 Typical molecular spectrum: Portion of absorption spectrum of SO 2 Contributions from: Electronic, Vibrational, Rotational, and Translational excitations

15. ΔE = h ν ΔE = hc/λ Fig 8.12 Quantized energy levels

16. Light has both: 1.wave nature 2.particle nature h = KE + Φ Photoelectric Effect Photon is a “particle” of light KE = h − Φ h KE e - Solved by Einstein in 1905

17. Fig 8.13 Threshold work functions for metals

18. Fig 8.14 Explanation of photoelectric effect For photons: E ∝ ν

19. Fig 8.15 Davisson-Germer experiment

20. Fig 8.16 The de Broglie relationship Wave-Particle Duality for: Light and Matter