nagle_phys2020_fa07_lecture17

nagle_phys2020_fa07_lecture17 - Current Density J v v i...

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1 16 Current Density J area current A i J = = v v J is caused by E, the electric field. In fact, E E J v v v σ ρ = = 1 Conductivity is the inverse of Resistivity. 17 One can then show that: iR V = Δ J E = They are equivalent. Macroscopic and Microscopic versions of Ohm’s Law. 18 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. A C B Which region A, B, or C has the greatest magnitude current i? A B C D) all three have the same i Clicker Question 19 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. A C B Which region A, B, or C has the greatest magnitude current density J? A B C D) all three have the same J. Clicker Question Region B has the largest current density J = i/A. All 3 regions have the same current i, so the region with the smallest A has the largest J. 20 Clicker Question A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper.

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This note was uploaded on 02/27/2008 for the course PHYS 2020 taught by Professor Dubson during the Fall '06 term at Colorado.

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nagle_phys2020_fa07_lecture17 - Current Density J v v i...

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