27.7 Wave-particle Duality Experiments show light has wave properties or particle properties.

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27.7 Wave-particle Duality Experiments show light has wave properties or particle properties. Diffraction Interference Photoelectric effect Compton scattering Einstein E particle = hf wave. 27.8 Wave Nature of Matter Do particles have wave properties? - PowerPoint PPT Presentation

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  • APHY201**27.7 Wave-particle Duality

    Experiments show light has wave properties or particle properties.DiffractionInterferencePhotoelectric effectCompton scattering

    Einstein Eparticle = hfwave

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  • APHY201**27.8 Wave Nature of Matter

    Do particles have wave properties?

    De Broglie wavelength of a particle

    Not noticed for macroscopic objects but important for microscopic objectsDiffraction of electrons from a crystalShown for other subatomic particles as well

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  • APHY201**X-ray diffraction 1912Electron diffraction 1927

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  • APHY201**27.10 Early Models of the AtomPlum-pudding model and Rutherfords experiment

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  • APHY201**27.10 Early Models of the AtomRutherfords planetary model - the atom is mostly empty space with a small positive nucleus.

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  • APHY201**27.11 Atomic Spectra

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  • APHY201**27.11 Atomic Spectra

    Each element has its own distinct set of spectral lines like human fingerprints or UPC labels

    Helium was discovered in the Sun (1868) before on the Earth (1882)The solar spectrum has lines that were not known on the Earth at that time

    Applications: astronomy, chemistry, forensics,

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  • APHY201**27.11 Atomic Spectra

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  • APHY201**27.12 The Bohr ModelWhy do atoms only emit and absorb at certain wavelengths? Why are atoms stable?

    Assumptions of Bohrs theory1. The e- moves in circular orbits around the nucleus2. Only certain orbits are stable3. Radiation is emitted when the e- jumps from a higher energy state to a lower one.4. The size of the orbits is determined by the e- orbital angular momentum.

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  • APHY201**27.12 The Bohr Model

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  • APHY201**27.13 The de Broglie Hypothesis

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