ECEN 215, Principles of Electrical EngineeringDr. Mina RahimianLecture# 8 Date: 9/18/13The CapacitorA capacitor is an electrical component that consists of two conductors separated by an insulator. When a voltage is applied between the two conductors, a positive charge is deposited on one conductor and a negative charge on the other. The amount of charge stored in the conductors is proportional to the voltage.Chapter 3, Capacitance and Inductance In this chapter, we consider energy storage elements. Similar to resistors these elements are passive; that is, they do not supply power. This chapter describes the relationship between voltage, current, power and energy for inductors and capacitors. In addition, it explains the effect of connecting these components in series and in parallel.Fluid flow analogy for a capacitorIn terms of fluid flow analogy, a capacitor represent a reservoir with an elastic mambrane separating the inlet and outlet. As he fluid flows into the inlet, the mambrane is stretched, creating a force ( analogous to capacitor volatge) that opposes further flow. The displaced fluid volume is analogous to the charge stored in the capacitor.voltage in terms of currentEx. At t=0, a 2-mA source is applied to an uncharged 2 micro-farad capacitor. Determinea) the capacitor voltage at t=30 ms.b) the energy stored in the capacitor at t= 30 ms.Power and EnergyImportant properties of capacitors1. A capacitor behaves as an open circuit when it's voltage is constant.2. The voltage across a capacitor cannot change instantaneously. (Capacitor voltage is continuous).series and parallel combination of capacitorsEx. Find the equivalent capacitance.voltage divider rule for capacitors:current divider rule for capacitorsEx. Find the voltage across each capacitor. Capacitors are not initially
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