EECE310 Chapter 1 Notes (F05)

EECE310 Chapter 1 Notes (F05) - College of Engineering,...

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Unformatted text preview: College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1- Introduction EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction How does electricity work? When there is free movement of the electron(s) surrounding an atom this is declared as electricity. Charge (q) is the fundamental property of matter. A negative charge in a single electron has a magnitude of 1.602 X 10-19 Coloumbs (C) EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Electric charge in motion is defined as current (i). Current is measured in amperés (A). Electrical current is the time rate of flow of electrical charge through a closed path. The closed path must have the ability to allow electrical charge to flow freely. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1- Introduction Important Note about the Flow of Current: When there’s a closed path (circuit elements are properly connected) within the network, current is allowed to flow through the circuit. When there’s an opening (a disconnection between circuit elements) within the network, current is not allowed to flow. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Materials which allow charge to flow freely are defined as conductors. Most metals are excellent conductors and are used to fabricate electrical wires. Primary examples of metals used as conductors are Aluminum (Al), Copper (Cu), Gold (Au), and Silver (Ag). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction In contrast to conductors, they are materials which do not allow charge to move easily. These types of materials are called insulators. Ceramics, glass, plastics, and rubber are all exemplars of materials used as insulators. Insulators provide resistance. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Also, there are materials which allow for the control of the flow of charge. These kinds of materials are called semiconductors. Popular semi-conducting substances are Gallium Arsenide (GaAs), Germanium (Ge), and Silicon (Si). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction There are three significant parameters that will be elucidated in this course: Current (i) Power (P) Voltage (v) All three parameters are time-varying quantities (i.e., i(t), P(t), and v(t)). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Current (i) is mathematically defined as: dq i= dt The number of electrons in one single coulomb is 6.25 X 1018. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Voltage (v) represents the potential energy of an electrical element. Voltage is the energy (w) transfer capability of the charge. Energy is measured in joules (J). Voltage is quantified in volts (V). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Voltage is described mathematically as: dw v= dq Voltage is measured in joules per coloumb. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Power (P) is defined as the time rate at which energy (w) is produced (active) or consumed (passive). The quantity for power is watts (W). Power is mathematically defined as: EECE 310 Preston D. Frazier, Ph.D., P.E., PMP dw P= dt College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Power is derived to be the product of voltage across a circuit element and the current traveling through it. dw dq dw P = vi = = dq dt dt All three parameters (i(t), P(t), and v(t)) can be positive or negative. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction There are two types of active circuit elements: Current sources and voltage sources. Batteries, generators, and transformers (a.k.a. X-formers) are examples of active circuit elements. There are three passive circuit elements: Capacitors (C) Inductors (L) Resistors (R) EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Capacitors (C) are components which store energy in a electric field. Their voltage and current relationship is prescribed as: 1 v = ∫ i ⋅ dt C EECE 310 Preston D. Frazier, Ph.D., P.E., PMP Capacitors’ electrical dimension are farads (F). College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Inductors (L) are two-terminal electrical components which stores energy in a magnetic field. Their voltage and current relationship is prescribed as: di v=L dt EECE 310 Preston D. Frazier, Ph.D., P.E., PMP Inductors’ electrical dimension are henries (H). College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Resistors (R) are elements which energy enters through the flow of current and is transformed into heat. Their voltage and current relationship is prescribed as: v = Ri Electrical measurement for resistors are ohms (Ω). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction There are three passive circuit elements are illustrated as: Capacitors (C) Inductors (L) Resistors (R) EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Active sources (current and voltage) fall into two categories, one is: Independent sources – The source maintains a specified current (i) or voltage (v) across its terminals regardless of the current (i) or voltage (v) flowing through it. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 1-Introduction Active sources (current and voltage) fall into two categories, the other is: Dependent sources – The source generates a current (i) or voltage (v) across its terminals that is determined by the current (i) or voltage (v) at a specific location in the circuit. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP ...
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