2026-09-14 10:43:03: Viruses 2

physics/Modern Physics/Bohr Model of Atomic Structure.md

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+[[Modern Physics]]
+# Summary
+* Atoms have a small positive nucleus made of protons and neutrons and are usually surrounded by electrons.
+* Nuclear notation: $^A_ZX$, Z protons A mass X atomic symbol 
+* Ion is atom with net charge.
+* In Bohr model, Coulomb force between nucleus and electrons provides centripetal force for circular orbit: $F_e=k\frac{q_1q_2}{r^2}$ supplies $F_{net}=m\frac{v^2}{r}$ 
+* Circumference must equal a whole number of de Broglies wavelength: $n\lambda=2\pi r$
+* Atomic structure here is only defined as energy levels, no probability functions yet.

physics/Modern Physics/Modern Physics.md

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+[[physics]]

physics/Modern Physics/Quantum Theory and Wave Particle Duality.md

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+[[Modern Physics]]
+# Summary
+* Quantum theory developed because classical physics can't explain atomic spectra, blackbody radiation or photoelectric effect.
+* Photons are electrically neutral massless particles.
+* $E=hf$, with $h$ being Planck's constant.
+* Photons travel at $c=$ 299792458 m/s (or $c=3*10^8$ for simplification) in a free space, and are slowed by a factor of the medium's index of refraction.
+* Particles like electrons show wave behavior, quantified by de Broglie wavelength $\lambda=h/p$. Wavelength increases as momentum decreases.
+* Quantum effects matter when a particles de Broglie wavelength is comparable to the system.
+* In bound systems, energy and momentum are discrete.