Chapter 33 Early Quantum Theory and models of atom
Chapter 33 Early Quantum Theory and Models of Atom
Revolution of classical physics World was well explained except a few puzzles? two dark clouds in the sky of physics M-Mexperiment y theory of relativity Black body radiation quantum theory Two foundations of modern physics Revolution of Q-theory: (1900-1926)>now?
Revolution of classical physics 2 World was well explained except a few puzzles? M-M experiment theory of relativity Black body radiation quantum theory Revolution of Q-theory: (1900 – 1926) → now? Two foundations of modern physics “two dark clouds in the sky of physics
Blackbody radiation All objects emit radiation -> thermal radiation 1)Total intensity of radiation oc T4 2)Continuous spectrum of wavelength Blackbody: absorbs all the radiation falling on it Idealized model Blackbody radiation -easiest
Blackbody radiation 3 All objects emit radiation → thermal radiation 1) Total intensity of radiation ∝ T4 2) Continuous spectrum of wavelength Blackbody: absorbs all the radiation falling on it Idealized model Blackbody radiation → easiest
Classical theories Wien's law nt=2.90x10'm K Experimen Intensity O Rayleigh-Jeans 6000K Wien Planck 3000K 1000 IR 2000 Wavelength(nm) Wavelength
Classical theories 4 Wien’s law: 3 2.90 10 PT m K Experiment Intensity Wavelength Wien Rayleigh-Jeans Planck
Planck,'s quantum hypothesis Planck formula(1900) 2hc25 hc/nk Max planck Completely fit the data Nobel 1918) Planck's constant: h=6.626x10-34. S The energy of any molecular vibration could be only some whole number multiply of hf
Planck’s quantum hypothesis 5 Planck’ formula (1900): Max Planck (Nobel 1918) 2 5 / 2 ( , ) 1 hc kT hc I T e Completely fit the data! 34 h 6.626 10 J s Planck’s constant: The energy of any molecular vibration could be only some whole number multiply of hf