Tag: Quantum physics
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Limitations of Bohr’s Quantum Theory of Spectra
Even though Niels Bohr’s quantum theory of spectra was regarded as one of the most revolutionary and successful theory of atomic dynamics, it was limited in the following ways: To overcome some of these limitations, Louis Victor de Broglie hypothesized that because photons have wave and particle characteristics, perhaps all forms of matter have wave…
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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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The Equivalence Principle & Black Holes
The equivalence principle is one of the laws of nature and it is connected with the nature of gravitation. In general relativity theory, the equivalence principle states that a gravitational field is locally equivalent to an accelerated frame. To be precise, it says that a freely falling observer or system will not experience the effects…
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Transmission Electron Microscope (TEM)
Electron beams are capable of providing crystallographic information about nanoparticle surfaces and can also be used to produce images of the surface, and they play this role in electron microscopes. The Operation of Transmission Electron Microscope In a transmission electron microscope the electrons from a source such as an electron gun enter the sample. They…
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Einstein’s Special Theory of Relativity
Einstein special theory of relativity is based on two assumptions: The first proposition asserts that all the laws of physics, those dealing with electricity and magnetism, optics, mechanics, thermodynamics, etc. will have the same mathematical form or be covariant in all coordinate frames moving with constant velocity relative to one another. This postulate is a…
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Quantum Mechanics vs. Newtonian Mechanics
Though quantum mechanics is a dynamical theory much like Newtonian mechanics, there are key differences between the two. In Newton’s mechanics, the state of a particle at t = 0 is specified by giving its initial position x (0) and velocity v (0) – only two numbers; Quantum mechanics demands an entire wavefunction ψ (x,…
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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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Yukawa Meson Theory of Nuclear Forces
In 1935 Yukawa proposed in his paper that there exist a meson field, that is, a field that is different from the electromagnetic field, whose quanta, the mesons have a finite mass, which is coupled to protons and neutrons in a manner analogous to the coupling of photons to charged particles. The exchange of these…
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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…
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Black Body Radiation
When a body is heated, it seen to radiate; in equilibrium the light emitted ranges over the whole spectrum of frequencies v, with a spectral distribution that depend on the frequency or equivalently on the wavelength of light λ and on the temperature. Gustav Kirchhoff proved a theorem when he showed by arguments based on…