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E. Nuclear and quantum physics

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2024/06/24 05:19
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E.1.1 Discrete Energy

Discrete Energy Level and Spectrums
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Photons are fundamental particles that make up all forms of electromagnetic radiation
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A photon is a massless quantum of electromagnetic energy
E.1.1-1 Diagrams and equations explaining the duality of light
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means that the energy is not transferred continuously but as discrete packets of energy
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each photon carries a specific amount of energy and transfers this energy all in one go
E.1.1-2 lined graph of emission spectrum
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Relation between emission spectrum and energy levels of electrons
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For example :
→ When hydrogen atom makes a transition from energy leven n=3 to n=2
→ The energy lost by one hydrogen atom is therefore :
E.1 Structure of the Atom

E.2.1 Photoelectric Effect:

E.2.1-1 Photoelectric effect from the metal surface
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Photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material.
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Electrons emitted in this manner are called photoelectrons.
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This effect was experimentally found by Rober Einstein, the results of the experiment disagree with classical electromagnetism, which predicts that continuous light waves transfer energy to electrons, which would then be emitted when they accumulate enough energy.
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The experiments instead show that the electrons are emitted only when the light has enough frequency, regardless of the light’s intensity or duration of exposure.
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Einstein came along with a new proposal - Wave-particle duality.
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That the beam of light in this is not a wave propagating through space but is made up of discrete energy packets, the photon particle.
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His detailed explanation was:
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Above the threshold frequency, incoming energy of photons = work function + kinetic energy
Emax=hf−ϕE_{\text{max}} = hf - \phi
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Stopping potential is the minimum negative voltage applied to the anode to stop the photocurrent.
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The maximum kinetic energy of the electrons equals the stopping voltage.
E.2 Quantum Physics

E.3.1 Radioactive Decay

Radioactive decay and Rate of decay
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Rate of decay is proportional to the number of particles left have not decayed
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Activity A : rate of radioactive decay
A=ΔNΔtA = \frac{\Delta N}{\Delta t}
Particles and Their Symbols
Types of decay:
1.
Alpha decay
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An unstable nuclei emits an alpha particle (the same configuration as helium nucleus)
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Proton number and nucleon number must be conserved.
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For example,
E.3 Radioactive Decay

E.4.1 Fusion and Fission

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The greater the binding energy per nucleon, the more stable the nucleus
E.4.1-1 Graph of nucleon numbers and and average binding energy per nucleon
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As shown in the figure above, nickel Ni-62 has the highest average binding energy per nucleon
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Elements to the left of Ni become more stable through nuclear fusion (light nucleis form into a heavier one)
Neutron induced fission
The nuclear fission reaction of uranium-235 is:
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01n+92235U→54140Xe+3894Sr+201n^{1}_{0}n + ^{235}_{92}U →^{140}_{54}Xe + ^{94}_{38}Sr + 2^{1}_{0}n
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01n+92235U→56144Ba+3689Kr+301n^{1}_{0}n + ^{235}_{92}U → ^{144}_{56}Ba + ^{89}_{36}Kr + 3^{1}_{0}n
The products are more or less random
If the products are unstable, they will further decay through alpha, beta, or gamma decay
E.4 Fission
Proton Proton Cycle
E.5.1-1
Energy released
Radiation pressure
E.5.1-2
Conditions for Fusion
Temperature
E.5.1-3
Pressure
Stellar mass and rate of fusion reaction
E.5 Fusion and Stars