Category: Quantum Physics
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Black Hole Evaporation Phenomenon
The discovery of a temperature seen by an accelerated fiducial observer adds a new dimension to the equivalence principle. Identical thermal effects can be expected to happen near the horizon of a very massive black hole. Nonetheless, in the case of a black hole a new phenomenon can take place, that is, evaporation. In contrast…
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Demystifying Compton Scattering
As the incident photon energy increases, the likelihood that it will undergo Photoelectric Effect decreases and the Compton Effect also referred to as Compton scattering becomes the dominant mode of interaction. In Compton scattering, the incident photon with energy hv0 interacts with a loosely bound (or free) electron from an outer shell and transfers some…
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Bohr’s Original Quantum Theory of Spectra
Regarded as one of the greatest discoveries, Niels Bohr’s original quantum theory of spectra was one of the most revolutionary and successful theory of atomic dynamics. Both Thomson and Rutherford recognized that the electrons must revolve about the nucleus in order to avoid falling into it. They along, with Bohr, realized that according to Maxwell’s…
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Spin Quantum Number
This property of atomic electrons was discovered through experimentation. The close observation of spectral lines revealed that each line was actually a pair of very closely-spaced lines, and what is referred to as fine structure was hypothesized to result from each electron “spinning” on an axis as if a planet. Electrons with different “spins” would…
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Bohr’s Correspondence Principle
Bohr’s correspondence principle states that predictions of quantum theory must correspond to the predictions of classical physics in the region of sizes where classical theory is known to hold. The classical sizes for length, mass, and time are on the order of centimeters, grams, and seconds and typically involve very large quantum numbers like can…
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Magnetic Quantum Number
The magnetic quantum number for an electron classifies which orientation its subshell shape is pointed. The “lobes” for subshells point in multiple directions. These different orientations are called orbitals. For the first subshell (s; l=0), which look like a sphere pointing in no “direction”, so there is only one orbital. For the second (p; l=1)…
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The Exclusion Principle
The exclusion principle states that no two electrons in an atom can have the same set of quantum numbers i.e. be in the same quantum state. Note, if this principle wasn’t valid, every electron would occupy the 1st atomic state (state of lowest energy), the chemical behaviour of the electrons would be significantly different and…
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Angular Momentum Quantum Number
A shell is made up of subshells. Subshells are regions of space where electron “clouds” are allowed to exist, and different subshells actually have different shapes. The first subshell is shaped like a sphere as illustrated in Fig 1.0(s) i.e. you can visualize it as a cloud of electrons surrounding the atomic nucleus in three…
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Principal Quantum Number
Symbolized by the letter n, this number describes the shell that an electron resides in. An electron “shell” is a region of space around an atom’s nucleus that electrons are allowed to exist, corresponding to the stable “standing wave” patterns of de Broglie and Bohr. Electrons may “leap” from shell to shell, but cannot exist…
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The Compton Effect
Compton Effect was a key experiment that provided the most direct evidence for the particle nature of radiation. Arthur Holly Compton, an American Physicist discovered that, radiation of a given wavelength (in the X-ray region) sent through a metallic foil was scattered in a manner not consistent with classical theory. As per classical theory, the…