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Unformatted text preview: ECE3710-D: Circuits & Electronics Class Notes (Ch. 1) Summer 2008 Devices (Ideal) Sources Independent Voltage Source (Vxx) Symbol I-V Curve ( V out = V DC ) +- V out I out V=V DC 2 4 6 8 10 V 2 4 6 8 10 I Voltage/Current-Controlled (a.k.a. Dependent) Voltage Source +- V out I out V= f( v x ) +- V out I out V= f( i x ) Independent Current Source (Ixx) Symbol I-V Curve ( I out = I DC ) V out I out I=I DC 2 4 6 8 10 V 2 4 6 8 10 I Voltage/Current-Controlled (a.k.a. Dependent) Current Source V out I out I= f( v x ) V out I out I= f( i x ) ** Voltage and current sources generating any periodic function, such as a sinusoid, square wave, triangle wave, etc. are also possible. The les- son here is that voltage sources are independent of the current through them, and that current sources are independent of the voltage across their terminals. ** Sinusoidal voltage sources may also represented by the following symbol: + ** A battery is a specific type of DC voltage source, repre- sented by the following sym- bol. V out I out V=V DC Passive Elements Resistor Symbol I-V Curve ( I = V R ) V I R 2 4 6 8 10 V 2 4 6 8 10 I Capacitor Symbol h i ( t ) = C d v ( t ) dt i V I C Inductor Symbol i ( t ) = 1 L R v ( t ) dt + i ( t ) V I L Diode Symbol I-V Curve I = I s e V A V T- 1 V I Active Devices (Will not be studied in this class.) C D E S B G M. J. Kroger 1 May 15, 2008 ECE3710-D: Circuits & Electronics Class Notes (Ch. 1) Summer 2008 Definitions Conductivity: ( ) = a measure of a materials ability to conduct electric current. = 1 Conductance: ( G ) = A measure of an objects or circuits ability to conduct an electric current between two points. It is dependent on and the geometric dimensions of the conducting object. Units: Siemens or Mhos. ( ). G = 1 R = A L = A L Resistivity: ( ) = a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electrical charge. = 1 Resistance: ( R ) = A measure of the degree to which an object opposes an electric current through it, i.e. the degree to which it impedes the flow of electrons. It is dependent on and the geometric dimensions of the conducting object. (As the cross sectional area of a wire is increased, its resistance will decrease. As the length of a wire increases, its resistance will increase.) Units: Ohms ( ) R = L A = 1 G Electrical Current: ( I ) = time rate of flow of positive electrical charge through a conductor or circuit element. Units: Amperes (A) [ A ] = [ C / sec ] i ( t ) = d q ( t ) dt q ( t ) = R t t i ( t ) dt + q ( t ) Voltage: ( V ) = Energy transferred per unit of charge that flows through the element....
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