Unformatted text preview: 206 Chapt. 27 Currents and Resistance 11. In the classical Drude model of conduction of electrons in metals, a macroscopic applied electric field vector E in the metal causes electrons to accelerate with acceleration for a mean time τ between collisions with ions, impurities, and defects in the metal. This acceleration imposes a nonrandom velocity on the electrons which causes net current flow. Collisions effectively cancel the nonrandom velocity by scattering the electron isotropically. We will call the nonrandom velocity just the velocity hereafter for brevity. The mean final velocity between collisions is vectora is vectoraτ and the average velocity is . This average velocity is in fact the drift velocity. Given the current density formula , the current density in the metal is . We call the conductivity of the metal. If the conductivity is independent of vector E , the metal is ohmic....
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 Fall '06
 Buchler
 Physics, Electron, Current, Resistance, Acceleration, Velocity, Electric charge, nonrandom velocity

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