Definitions of capacitor

  1. An electronic device that can store electricalcharge. The charge stored Q in Coulombs is related to thecapacitance C in Farads and the voltage V across the capacitorin Volts by Q = CV.The basis of a dynamic RAM cell is a capacitor. They arealso used for power-supply smoothing ( or " decoupling"). Thisis especially important in digital circuits where a digitaldevice switching between states causes a sudden demand forcurrent. Without sufficient local power supply decoupling,this current " spike" cannot be supplied directly from thepower supply due to the inductance of the connectors and sowill cause a sharp drop in the power supply voltage near theswitching device. This can cause other devices to malfunctionresulting in hard to trace glitches.