Lecture_2 - DC circuits, Kirchhoffs Laws alternating...

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1 DC circuits, Kirchhoff’s Laws CHM6158C - Lecture 2 alternating current (AC), direct current (DC) DC circuits resistors Kirchhoff’s Laws note on impedance
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2 Electric current Movement of electrons in a conductor Examples of good conductors: copper aluminum silver Cable enclosed with an insulating material (e.g. polyethylene) http://www.hydroquebec.com/learning/images/quest- ceque/i_schema_atome.gif Units : Charge (Q) Coulomb (C) 1.603x10 -19 C Voltage (V) Volts (V) 1 V = 1 J/C Current (I) Amperes (A) 1 C/s Power (P) Watts (W) P = IV At what speed does electricity propagate? A current of 100 mA can be lethal !
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3 Conductivity Conductivity = measure of a material’s ability to conduct an electrical current Inverse: Resistivity vs. resistance silver > copper > aluminum Resistivity = measure of how strongly a material opposes the flow of electrical current (units: Ω m) (inherent of material) J E = ρ Magnitude of electric field (V) Magnitude of current density (A) Resistance = measure of how strongly a material opposes the flow of electrical current (units: Ω ) (dependent on cross-section and length of material) I V R = OHM’s LAW Strange units – why?
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This note was uploaded on 07/30/2011 for the course CHM 6158 taught by Professor Polfer during the Spring '11 term at University of Florida.

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Lecture_2 - DC circuits, Kirchhoffs Laws alternating...

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