ECE 345 Lecture Notes - Lecture 16: Inductor, Short Circuit, Wilhelm Eduard Weber
9 Nov 2017
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Document Summary
Capacitors: capacitors are two terminal devices and are open circuits which terminate in large area metal plates separated by an insulator (air, paper, plastic, ceramic, etc. ). The large area metal plates can store charge (positive charge on one plate and negative charge on the other plate) leading to an electric field between the plates as shown in figure 2. The energy in the capacitor is stored in this electric field. The structure of a capacitor consists of two electrically separated metal plates of area, a. The capacitance, c, has units of farads (f) and is given by: A d where = dielectric constant (or permittivity) 0 r where r = relative dielectric constant and 0 = 8. 85 10-12 (f/m) = permittivity of free space. With an applied voltage across a capacitor, the metal plates collect charge which leads to an electric field, e. The symbol for a capacitor is shown on the right.
