Mechatronic Systems Engineering 2201A/B Lecture Notes - Lecture 21: Farad, Electric Field, Displacement Current
15 Jan 2020
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Document Summary
A capacitor is a passive element that stores energy in the form of an electric field. A capacitor is typically constructed from two sheets of conductor separated by an insulator. When a current flows through a capacitor, the opposite charges are actually accumulated on the opposite plates. As charge builds up, voltage appears across the capacitor. A capacitor is analogous to a reservoir with elastic membrane separating inlet and outlet. As the fluid flows into the inlet, the membrane is stretched and the resulting force opposes further flow. In an ideal capacitor, the voltage across the capacitor is proportional to the charge stored on the plates: One farad is a very large amount of capacitance. In practice, the capacitors usually have the capacitance between. For an ideal capacitor, the relationship between voltage and current is: In particular, if voltage is constant the current is zero: thus, for a constant voltage, the ideal.
