PHYS 241 Lecture Notes - Lecture 5: Electric Field, Energy, Current Density
21 Oct 2014
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Document Summary
Electrodynamics: free electrons that are moving in conductors. Assumptions about conductors, e=0, is no longer true: e =/= 0 in conductors now, because the charges have to move, electric field is required for charges to move. This flow of charges is current: current is net amount of charge that passes through a given surface per unit time. Units of current: coulombs/second=amperes (a: typically, computers, information, current is a few microamps, for energy transfer, current is milliamps to amps. In conductors: electrons reach terminal velocity called drift velocity,": number density: electrons per volume, estimate: Resistors: resistance is an extrinsic property, resistivity: intrinsic, related to local electrical properties, relationship between resistance and resistivity. Ohm"s law (not universal, just valid in some specific cases: for some circumstances, it is observed that v is increased, current increases proportionally. Dr. sandhu office hours: tuesday 11:30-12:30, thursday 1:30-2:30. Monday march 8, 5:00pm and friday march 12 5:00pm.
