quantum physics. black body radiation intensity of blackbody radiation classical rayleigh-jeans law...
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![Page 1: Quantum Physics. Black Body Radiation Intensity of blackbody radiation Classical Rayleigh-Jeans law for radiation emission Planck’s expression h = 6.626](https://reader033.vdocument.in/reader033/viewer/2022061511/56649d5f5503460f94a3f33f/html5/thumbnails/1.jpg)
Quantum Physics
![Page 2: Quantum Physics. Black Body Radiation Intensity of blackbody radiation Classical Rayleigh-Jeans law for radiation emission Planck’s expression h = 6.626](https://reader033.vdocument.in/reader033/viewer/2022061511/56649d5f5503460f94a3f33f/html5/thumbnails/2.jpg)
Black Body Radiation
Intensity of blackbody radiationClassical Rayleigh-Jeans law forradiation emission
Planck’s expression
h = 6.626 10-34 J · s : Planck’s constant
Assumptions: 1. Molecules can have only discrete values of energy En;
2. The molecules emit or absorb energy by discrete packets - photons
![Page 3: Quantum Physics. Black Body Radiation Intensity of blackbody radiation Classical Rayleigh-Jeans law for radiation emission Planck’s expression h = 6.626](https://reader033.vdocument.in/reader033/viewer/2022061511/56649d5f5503460f94a3f33f/html5/thumbnails/3.jpg)
Quantum energy levels
Energy
E
0
1
3
4
5
2
n
hf
2hf
3hf
4hf
0
5hf
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Photoelectric effect
Kinetic energy of liberated electrons is
where is the work function of the metal
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Atomic Spectra
a) Emission line spectra for hydrogen, mercury, and neon;b) Absorption spectrum for hydrogen.
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Bohr’s quantum model of atom
+e
e
r
F v
1. Electron moves in circular orbits.2. Only certain electron orbits are stable.3. Radiation is emitted by atom when electron jumps from a more energetic orbit to a low energy orbit.
4. The size of the allowed electron orbits is determined by quantization of electron angular momentum
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Bohr’s quantum model of atom
+e
e
r
F v
Newton’s second law
Kinetic energy of the electron
Total energy of the electron
Radius of allowed orbits
Bohr’s radius (n=1)
Quantization of the energy levels
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Bohr’s quantum model of atom
Orbits of electron in Bohr’s model of hydrogen atom.
An energy level diagram for hydrogen atom
Frequency of the emitted photon
Dependence of the wave length
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The waves properties of particles
Louis de Broglie postulate: because photons have both wave and particle characteristics, perhaps all forms of matter have both properties
Momentum of the photon
De Broglie wavelength of a particle
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Example: An accelerated charged particle
An electron accelerates through the potential difference 50 V. Calculate itsde Broglie wavelength.
Solution:
Energy conservation
Momentum of electron
Wavelength