Recent content by Tweej

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    Graduate Have we derived the Gravitational constant via General Rel?

    Okay, so that's interesting. G has no definition with regards to other fundamental constants because General Rel is a unitless theory. To assign it a set of units would be to arbitrarily pick the mass of one particle over another, as opposed to the charge of an electron in QM which is the...
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    Graduate Have we derived the Gravitational constant via General Rel?

    My friend and I were discussing this, and google didn't seem to reveal any result. Much like how Bohr's theory managed to derive the Rydberg constant without much effort, has the gravitational constant been found in terms of other quantities yet? It just seems bizarre that Newton proposed a...
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    Undergrad What makes the change of sign in Hall?

    In a semiconductor, you can have either negative charge carriers (conduction electrons) or positive charge carriers (holes - absence of charge carriers). If you know about energy bands, then you'll know that when an electron is given enough energy, it jumps from the valance band to the...
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    Graduate Absorption in Indirect Bandgaps

    Correct me if I'm wrong, but I assumed that when making the jump, the electron could either absorb or emit a phonon. Meaning that when emitting a phonon, ħωphoton = Eg + ħωphonon And absorbing ħωphoton = Eg - ħωphonon Please wait for someone else to respond to my comment before you take it...
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    Graduate Magnetic Dipole less than that of the Bohr Magneton

    Thought so. Thank you very much for clarifying.
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    Calculations of a half loop electromagnet

    That makes sense! Thank you very much for the help Hesch!
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    Graduate Magnetic Dipole less than that of the Bohr Magneton

    Hey there, The basic unit for magnetic dipoles is the bohr magneton μB = e ħ / 2 me Is it possible to have a magnetic dipole moment of a fraction of a bohr magneton, say, 0.5 μB Is it possible because the mp of a proton is greater than that of an electron, so following the same formula, its...
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    Calculations of a half loop electromagnet

    So Ems = ρ * A * π * D/2 * g * δ = VAirGap * Ed = 1/2 * δ * A * 2 (as there are two air columns) * Ed D/2 * g * ρ * π = 1/2 B * H D = (B * H) / (g * ρ * π) Then at this point I have one more question Do we have H = M, B = mu_0 H Or the Biot Savart law for B from i Thank you for the help
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    Calculations of a half loop electromagnet

    Homework Statement This is a past exam question which I just for the life of me can't figure out. http://tinypic.com/r/2eq6ryo/8Homework Equations My guess is that the energy of the magnetisation is equal to the gravitational energy Relevant Equations: Ems = Mass * g * δ Where Mass = ρ *...