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Chapters 30, 31 Light Emission Light Quanta. Light Emission Topics. Chapter 31. Excitation Emission Spectra Incandescence Absorption Spectra Fluorescence Phosphorescence Lasers. Spectral lines. Spectra. Let There Be Light!. Excitation. E = hf. h = 6.6 x 10 -34 j-s. Lines.

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Chapters 30 31 light emission light quanta
Chapters 30, 31Light EmissionLight Quanta


Light emission topics
Light Emission Topics

Chapter 31

  • Excitation

  • Emission Spectra

  • Incandescence

  • Absorption Spectra

  • Fluorescence

  • Phosphorescence

  • Lasers





Excitation
Excitation

E =hf

h = 6.6 x 10-34 j-s










Clicker questions
Clicker Questions

  • Electrons with the greater potential energies with respect to the atomic nucleus are:

    • A) inner electrons.

    • B) outer electrons.

    • C) both the same, actually

  • 2) Light is emitted when an electron

    • A) makes a transition to a lower energy level.

    • B) is boosted to a higher energy level.

    • C) neither of these

  • 3) Which color of light carries the most energy per photon?

    • A) violet B) red C) blue D) green E) all the same


Clicker questions1
Clicker Questions

  • 4) Atoms can be excited by

    • A) photon impact.

    • B) electron impact.

    • C) thermal agitation.

    • D) all of these

    • E) none of these

  • 5) An atom that absorbs a photon of a certain energy can then emit

    • A) only a photon of the same or higher energy.

    • B) only a photon of the same or lower energy.

    • C) a photon of any energy.

    • D) only a photon of that energy.

  • 6) The variety of colors seen in a burning log comes from the variety of

    • A) multi-layered incandescent surfaces.

    • B) absorbing gases between the log and the viewer.

    • C) chemicals in the log.

    • D) electron transitions in various atoms.

    • E) temperatures.


Light quanta topics
Light Quanta Topics

Chapter 31

  • Quantization & Planck’s Constant

  • Photoelectric Effect

  • Wave-Particle Duality

  • Double Slit Experiment

  • Electron Diffraction

  • Uncertainty Principle

  • Complementarity


Quantization planck s constant
Quantization & Planck’s Constant

Energy is only given off at the atomic level in discrete increments where E = hf





Wave particle duality1
Wave/Particle Duality

Lois de Broglie (1924)

If waves (i.e. light) can act as a particle when it interacts with matter, then a particle can act like a wave when traveling through space :

Wavelength = h/momentum , l = h/p,

h = 6.6 x 10-34 j-s


Uncertainty principle
Uncertainty Principle

DpDx >= h/2p

DEDt>=h/2p


Clicker questions2
Clicker Questions

  • Which of the following photons has the greatest energy?

    • A) blue light

    • B) infrared

    • C) green light

    • D) ultraviolet

    • E) red light

  • 2) In the photoelectric effect, the brighter the illuminating light on a photosensitive surface, the greater the

    • A) number of ejected electrons.

    • B) velocity of ejected electrons.

    • C) both of these

    • D) neither of these

  • 3) In the photoelectric effect, the greater the frequency of the illuminating light, the greater the

    • A) number of ejected electrons.

    • B) maximum velocity of ejected electrons.

    • C) both of these

    • D) neither of these


Clicker questions3
Clicker Questions

  • 4) In the double-slit experiment with electrons, the electrons arrive at the screen in a

  • A) particle-like way with a pattern that is particle-like.

    • B) wave-like way with a pattern that is wave-like.

    • C) wave-like way with a pattern that is particle-like.

    • D) particle-like way with a pattern that is wave-like.

  • 5) According to the uncertainty principle, the more we know about a particle's momentum, the less we know about its

    • A) mass.

    • B) location.

    • C) kinetic energy.

    • D) speed.

    • E) none of these

  • 6) Which of the following is not quantized?

    • A) electric charge

    • B) radiation

    • C) energy

    • D) number of people in a room

    • E) All are quantized.


Clicker questions4
Clicker Questions

  • 7) When a clean surface of potassium metal is exposed to blue light, electrons are emitted. If the intensity of the blue light is increased, which of the following will also increase?

    • A) the number of electrons ejected per second

    • B) the time lag between the absorption of blue light and the start of emission of the electrons

    • C) the maximum kinetic energy of the ejected electrons

    • D) the threshold frequency of the ejected electrons

    • E) none of these

  • 8) A bullet and a proton have the same momentum. Which has the longer wavelength?

    • A) the bullet

    • B) the proton

    • C) Both have the same wavelength.


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