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Unformatted text preview: 1 Physics 208N-004 Lecture #13 – 9 February 2011 Chapter 25: 1-5 Battery, Current, Ohm’s Law, Resistively and Power • The Electric Battery • Electric Current • Ohm’s Law: Resistance and Resistors • Resistivity • Electric Power • Power in Household Circuits • Alternating Current • Microscopic View of Electric Current: Current Density and Drift Velocity • Superconductivity • Electrical Conduction in the Nervous System Volta discovered that electricity could be created if dissimilar metals were connected by a conductive solution called an electrolyte. This is a simple electric cell. 25-1 The Electric Battery A battery transforms chemical energy into electrical energy. Chemical reactions within the cell create a potential difference between the terminals by slowly dissolving them. This potential difference can be maintained even if a current is kept flowing, until one or the other terminal is completely dissolved. Several cells connected together make a battery, although now we refer to a single cell as a battery as well. 25-1 The Electric Battery Electric current is the rate of flow of charge through a conductor: The instantaneous current is given by: A complete circuit is one where current can flow all the way around. Note that the schematic drawing doesn’t look much like the physical circuit! 25-2 Electric Current Unit of electric current: the ampere, A: 1 A = 1 C/s ....
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This note was uploaded on 09/18/2011 for the course PY 208M 87878 taught by Professor George during the Spring '09 term at N.C. State.
- Spring '09