Term of the Moment
carpal tunnel syndrome
Definition: capacitor
An electronic component that stores an electric charge that is released to keep voltage levels stable. Capacitors come in a huge variety of sizes and types for use in regulating power as well as for conditioning, smoothing and isolating signals. They are made from different materials, and virtually every electrical and electronic system uses them.
Somewhat Like a Battery
Capacitors act like storage batteries that charge and discharge rapidly. Made of two plates separated by a thin insulator or sometimes air, when one plate is charged negative and the other positive, a charge builds up and remains after the current is removed. When power is required, the circuit is switched to conduct current between the plates, and the charge is released. See ultracapacitor.
Silver Batteries
Many Applications
Somewhat Like a Battery
Capacitors act like storage batteries that charge and discharge rapidly. Made of two plates separated by a thin insulator or sometimes air, when one plate is charged negative and the other positive, a charge builds up and remains after the current is removed. When power is required, the circuit is switched to conduct current between the plates, and the charge is released. See ultracapacitor.
Looking like "silver cans," and acting like miniature storage batteries, dozens of capacitors are found on circuit boards such as this. Wired between power and ground planes, they quickly charge up when the device is turned on. When an application demands extra processing, more transistors switch simultaneously and the capacitors release their charge. (Image courtesy of NVIDIA Corporation.)
DRAM memory chips use capacitors to hold a charge (see dynamic RAM), and thousands of tiny capacitors as small as a grain of sand are etched into all kinds of chips. CPU circuits, which are mostly transistors and resistors, may also contain capacitors. Signal processing uses capacitors and resistors to smooth transmission spikes and huge capacitors weighing up to 100 pounds smooth out the current in the electrical grid. See tantalum capacitor and ferroelectric capacitor.