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Max Planck From Planck’s work on Blackbody Radiation, he proposed that the energy of light is quantized Quantization is an idea that energy comes in bundles or discrete amounts Energy is quantized This idea disagreed with established (traditional) physics
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Modern PhysicsChapters 38-40
Wave-Particle Duality of Light Young’s Double Slit Experiment (diffraction)
proves that light has wave properties So does Interference and Doppler Effect
Photoelectric Effect proves that light has properties of particles
Max Planck From Planck’s work on Blackbody Radiation, he
proposed that the energy of light is quantized
Quantization is an idea that energy comes in bundles or discrete amounts Energy is quantized
This idea disagreed with established (traditional) physics
Photoelectric Effect Light shining on a photo-sensitive metal plate
will emit electrons.
Photoelectric Effect
Photoelectric Effect Frequency must be above a minimum
(threshold) frequency
Brighter light (higher intensity) produces more electrons, but with the same energy
Light with higher frequency will emit electrons with higher energy
Photoelectric Effect Law of Conservation of Energy must be
followed Energy must be related to frequency
Law of Conservation of Momentum must also be followed Light has momentum
Photoelectric Effect Einstein used previous work by Max Planck
to explain Photoelectric Effect (Nobel Prize 1921)
Proposed that discrete bundles of light energy are photons
Energy is proportional to Frequency E=hf
h, Planck’s Constant 6.63 x 10-34 J*s
Equations
fc
hchfE
cf
Compton Effect 1923 Arthur Compton uses photon
model to explain scattering of X-rays
Determines equation for momentum of a photon
Compton Effect X-ray photon strikes an electron at rest
After the collision both the electron and X-ray photon recoil (move) in accordance with Laws of Conservation of Momentum and Energy
The photon transfers some momentum to the electron during collision.
Compton Effect Change in wavelength
of photon must be related to momentum
Magnitude of Photon Momentum:
h
chfmvp
de Broglie Wavelength 1923, graduate student, Louis de Broglie
suggested that if light waves could exhibit properties of particles, particles of matter should exhibit properties of waves
Used same equation as momentum of photon
mvh
ph
Standard Model Matter is classified into 2 types
Hadrons and Leptons
The Quark Family, also called Hadrons, are classified further into 2 types Baryons and Mesons
Quarks Six quarks
Up, Down, Top, Bottom, Strange, and Charm
Up, Charm, and Top all have +2/3e charge Down, Strange, and Bottom all have -1/3e charge
They all have different masses
Baryons Baryons are comprised (made of) three
quarks The total charge for any baryon is the net
charge of the three quarks together (-1, 0, +1, +2)
Examples: uud = +2/3, +2/3, -1/3 = +1 = proton udd = +2/3, -1/3, -1/3 = 0 = neutron
Mesons Mesons are comprised of a quark and its
antiquark
Antimatter Particles that have the same mass but opposite
charge of their matter partner Have same symbol as matter but with added bar
above symbol Up quark, u up antiquark, ū
Leptons Leptons are separated into six flavours
Electron, Muon, and Tau all have -1 charge Electron neutrino, muon neutrino, and tau
neutrino all have 0 charge
Annihilation When matter and antimatter particles collide,
they annihilate each other and produce energy
E=mc2
kg J (use equation) u eV (use conversion on Reference Tables)
Fundamental Forces Strong Force
Force that holds nucleons (protons and neutrons) together
Short range
Weak Force Associated with radioactive decay Short Range
Fundamental Forces Gravitational Force
Attractive only Long distance range (think planets)
Electromagnetic Force Attractive and repulsive force on charged particles Long range (think stars)
Mass Defect and Binding Energy Mass Defect
Difference between the actual mass of the atom and the sum of the individual masses of the protons, neutrons, and electrons.
Binding Energy The amount of energy that must be supplied to a
nucleus to completely separate its nuclear particles
Mass defect converted to energy, E=mc2
Mass-Energy Conversion E=mc2
Kg J u eV
1 u = 1.4924 x 10-10 J
1 u = 9.31 x 108 eV = 931 MeV