ECT 2440 Chapter Notes - Chapter 3: Capacitor Types, Dielectric, Oliver Heaviside
Document Summary
Capacitors are constructed by separating two conducting plates, which are usually metallic, by a thin layer of insulating material. The insulating material between the plates, called a dielectric, can be air, Mylar, polyester, polypropylene, mica, or a variety of other materials. As current flows through a capacitor, charges of opposite signs collect on the respective plates. Positive charge on one plate is balanced by negative charge of equal magnitude on the other plate. In an ideal capacitor, the stored charge q is proportional to the voltage between the plates: capacitance c, which has units of farads (f). The relationship between current and voltage is. Charge as a function of time is given by. Voltage as a function of time is given by. Energy stored in the capacitance that can be returned to the circuit: Two alternative expressions for the stored energy: and. Capacitances in parallel are combined like resistances in series: Capacitances in series are combined like resistances in parallel: