Radium source emits alpha particles, pass lead block, hit gold foil, lead sulfide screen of microscope detects particles.
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What conclusions were made from alpha scattering experiment?
Slower particles - more deflected at greater angles and distance, small charge nucleus - less strong scattering.
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What pattern did scattering experiment show?
As scatter angle rose, no scattered inversely fell.
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What did alpha scattering show about nucleus?
Nucleus is dense and small in size as most alpha particles didn't hit it.
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What was the maximum size of the nucleus from the scattering experiment?
Max size of nucleus = distance of closest approach r. E=kqQ/r
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How did electron scattering experiment work?
In X-Ray tube electrons are boiled off filament and accelerate to positive target producing X rays which lose PE and gain KE.
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What is relativistic momentum?
Momentum = γmc. Relativistic momentum increases over linear as v->c.
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What is formula for total energy?
Total energy = ( γ -1)mc² + mc². Erest is mass energy.
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What do linear accelerators do?
Linear accelerator accelerates electrons to high energies. Travel is timed so PD can switch from electrodes to continue journey. As v->c length of electrodes rises.
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What is PD inside and outside linear accelerator electrodes?
In electrodes PD is zero, across electrodes PD varies as a sine wave.
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What is the mass of the nucleus? What are isotopes?
Mass of nucleus = mass - mass of electrons. Electrons determine chemical properties. Isotopes have different neutron and nucleon number, unstable possibly.
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What are A, Z, and X for each element?
A is nucleon number, Z is proton number, X is chemical symbol.
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What are quarks for protons and neutrons?
Proton = up up down, neutron = up up down. Up = 2/3 e down = 1/3 e
Electron hits quark in nucleon and exchange of high energy photons creates jet of particles, mesons released. Electron scattered.
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What do gluons do?
Gluons - quarks held together by gluons which attract quarks to each other. Keeps protons together and leads to strong interaction to make nucleons attract.
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How were anti-neutrinos found from B- decay?
Beta-minus decay when nucleus has too many neutrons. Electron released. Antineutrino carries extra energy. Mass, charge, lepton number, and energy conserved.
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Why do neutrinos interact weakly with matter?
Neutrinos interact weakly with matter due to no charge and tiny mass.
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What is annihilation?
Annihilation - In B+ decay positrons produced, collide with electron destroying matter. Gamma ray photons carry energy in opposite directions. Charge, momentum, energy, lepton no conserved. E=2mc^2
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What is creation?
Gamma ray photon near massive nucleus with p=E/c splits. Nucleus takes away momentum and positron + electron made.
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How does speed and energy impact paths of deflected particles?
High speed reduces curvature of electrons, as kinetic energy lost, tracks spiral.
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How does thermionic emission work?
Electrons have discrete energy levels. Electrons accelerate to wire grid from filament, decelerate to anode, ammeter measures no of electrons. Tube contains low pressure gas so electrons collide with atoms.
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In thermionic emission why does anode current drop across voltage?
Anode current drops at Vc, 2Vc, and 3Vc as electrons have inelastic collisions with 1-3 gas molecules so less have enough energy to hit ammeter.
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How does electron diffraction relate to linear accelerators?
λ=h/p. as electrons pass linear accelerator magnetic field deflects to nucleus where they are diffracted. Minimum at sin0=1.22λ/d (d= diameter of nucleus_
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When does λ=h/p change?
λ=hc/E for relativistic speeds.
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How does kinetic energy and momentum formula relate?
Ek=h^2/2mλ^2 as p=h/λ and Ek=p^2/2m
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How does nucleus size affect energy?
The smaller the nucleus, the smaller the wavelength, so larger momentum and energy. Size of nucleus determines discrete energy levels.
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Why are atoms not smaller?
Electrons bound, as electrons are bound standing waves require momentum and KE, KE rises as atom is smaller. As atom halves in size, PE doubles but KE quadruples. Electron escapes when KE>PE
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What is formula for energy at each level and actual formula?
En = n^2 * h^2/2m(λ)^2, for hydrogen En = -13.6eV/n^2
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Other cards in this set
Card 2
Front
How did the alpha scattering experiment work?
Back
Radium source emits alpha particles, pass lead block, hit gold foil, lead sulfide screen of microscope detects particles.
Card 3
Front
What conclusions were made from alpha scattering experiment?
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