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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: ( σ ) = a measure of a material’s ability to conduct electric current. σ = 1 ρ Conductance: ( G ) = A measure of an object’s or circuit’s ability to conduct an electric current between two points. It is dependent on σ and the geometric dimensions of the conducting object. Units: Siemens or Mhos. ( ). G = 1 R = A ρ L = σ A L Resistivity: ( ρ ) = 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. ρ = 1 σ 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 ρ 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 ( Ω ) R = ρ 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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- Spring '07
- Volt, Resistor, Thévenin's theorem, Voltage source, Current Source, Circuits & electronics, M. J. Kroger