Related topics: energy

Shrinking qubits for quantum computing with atom-thin materials

For quantum computers to surpass their classical counterparts in speed and capacity, their qubits—which are superconducting circuits that can exist in an infinite combination of binary states—need to be on the same wavelength. ...

Improving low-loss dielectric measurement technique

Scientists from NPL have developed improvements to a technique for measuring dielectric permittivity and loss of materials at MHz frequencies. The method used is named after two NPL scientists who developed in the 1930, Hartshorn ...

Researchers develop computational model to build better capacitors

Researchers at North Carolina State University have developed a computational model that helps users understand how changes in the nanostructure of materials affect their conductivity—with the goal of informing the development ...

page 1 from 9


A capacitor (formerly known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator); for example, one common construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used as parts of electrical circuits in many common electrical devices.

When there is a potential difference (voltage) across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them.

The capacitance is greatest when there is a narrow separation between large areas of conductor, hence capacitor conductors are often called "plates," referring to an early means of construction. In practice, the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, resulting in a breakdown voltage, while the conductors and leads introduce an undesired inductance and resistance.

Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.

This text uses material from Wikipedia, licensed under CC BY-SA