final09 - Physics 361 Final exam December 7 2009 answers in...

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Unformatted text preview: Physics 361 Final exam December 7, 2009 answers in [[..]]. You may consult notes that you yourself have written. F.1 Comparing two metals, short answer Two free-electron-like metals, A and B, have a single valence electron, but the metal B has three times as many electrons per unit volume as metal A. Briefly justify your answers: a) (2 points) What is the electric conductivity of metal B relative to A, assuming the scattering time τ is the same for both? [[3]] b) (2 points) What is the electronic specific heat c v ( i.e., heat capacity per unit volume) of B relative to A? [[3 1 / 3 ]] c) (2 points) What is the Hall coefficient of B relative to A, i.e., the trans- verse electric induced by a given magnetic field and a longitudinal cur- rent? [[1/3]] F.2 Critical magnetic field The energy per unit volume in a supercon- ductor is roughly- Δ(Δ / E F ) n , where n is the density of electrons, the pair energy is Δ and the Fermi energy is E F . If a magnetic field H is applied, it is excluded from virtually all of the interior, thus creating a stronger field outside the sample. Thus H field is increased by a factor of order unity in a volume comparable to the sample volume Ω. a) (4 points) From this information, give a rough estimate of the maximum magnetic field that can be applied such that the superconducting state...
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This note was uploaded on 03/02/2010 for the course PHYSICS 336 taught by Professor Pucker during the Spring '10 term at King's College London.

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final09 - Physics 361 Final exam December 7 2009 answers in...

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