# News tagged with capacitance

## Mystery of negative capacitance in perovskite solar cells solved

On the verge of outcompeting current thin-film solar cells, perovskite solar cells seem to embody an ideal solar cell with high efficiency and low cost. However, they have poor long-term stability, which remains a challenge. ...

## Touch-sensitive, elastic fibers offer new interface for electronics

Researchers from North Carolina State University have created elastic, touch-sensitive fibers that can interface with electronic devices.

## Apple patent reveals idea for fingerprint technology

(Tech Xplore)—"Capacitive fingerprint sensor including an electrostatic lens" is the title of the patent filed in September 2014.The inventor listed is Jean-Marie Bussat. This is being talked about in this week's tech press ...

## Capacitance

In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored (or separated) for a given electric potential. A common form of energy storage device is a parallel-plate capacitor. In a parallel plate capacitor, capacitance is directly proportional to the surface area of the conductor plates and inversely proportional to the separation distance between the plates. If the charges on the plates are +q and −q, and V gives the voltage between the plates, then the capacitance is given by

The SI unit of capacitance is the farad; 1 farad is 1 coulomb per volt.

The energy (measured in joules) stored in a capacitor is equal to the work done to charge it. Consider a capacitor of capacitance C, holding a charge +q on one plate and −q on the other. Moving a small element of charge dq from one plate to the other against the potential difference V = q/C requires the work dW:

where W is the work measured in joules, q is the charge measured in coulombs and C is the capacitance, measured in farads.

The energy stored in a capacitor is found by integrating this equation. Starting with an uncharged capacitance (q = 0) and moving charge from one plate to the other until the plates have charge +Q and −Q requires the work W:

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