Editing Electrolytic capacitor (section)

===Capacitance and volumetric efficiency===
[[Image:Parallel plate capacitor.svg|thumb|right|A dielectric material is placed between two conducting plates (electrodes), each of area '''''A''''' and with separation '''''d'''''.]]
Electrolytic capacitors are based on the principle of a "plate capacitor" whose capacitance increases with larger electrode area A, higher dielectric [[permittivity]] ε, and thinness of dielectric (d).

:<math>C = \varepsilon \cdot \frac{A}{d}</math>

The dielectric thickness of electrolytic capacitors is very small, in the range of [[Meter|nanometers]] per volt. On the other hand, the voltage strengths of these oxide layers are quite high. With this very thin dielectric oxide layer combined with a sufficiently high dielectric strength the electrolytic capacitors can achieve a high volumetric capacitance. This is one reason for the high capacitance values of electrolytic capacitors compared to conventional capacitors.

All etched or sintered anodes have a much higher surface area compared to a smooth surface of the same area or the same volume. That increases the capacitance value, depending on the rated voltage, by a factor of up to 200 for non-solid aluminium electrolytic capacitors as well as for solid tantalum electrolytic capacitors.<ref name=Voltage>A. Albertsen, Jianghai Europe, Keep your distance – Voltage Proof of Electrolytic Capacitors, [http://jianghai-europe.com/wp-content/uploads/3-Jianghai-Europe-E-Cap-Voltage-Proof-AAL-2012-10-30.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20130108014604/http://jianghai-europe.com/wp-content/uploads/3-Jianghai-Europe-E-Cap-Voltage-Proof-AAL-2012-10-30.pdf |date=2013-01-08 }}</ref><ref name="KDK">{{Cite web|url=http://www.kdk.com/e/productinfo/specifications/c-03-02-03-e.pdf|title=KDK, Specifications for Etched Foil for Anode, Low Voltage}}</ref><ref name="Horacek">I.Horacek, T.Zednicek, S.Zednicek, T.Karnik, J.Petrzilek, P.Jacisko, P.Gregorova, AVX, High CV Tantalum Capacitors - Challenges and Limitations [http://www.avx.com/docs/techinfo/highcvtant.pdf] {{Webarchive|url=https://web.archive.org/web/20140309021406/http://www.avx.com/docs/techinfo/highcvtant.pdf|date=2014-03-09}}</ref> The large surface compared to a smooth one is the second reason for the relatively high capacitance values of electrolytic capacitors compared with other capacitor families.

Because the forming voltage defines the oxide layer thickness, the desired voltage rating can be produced very simply. Electrolytic capacitors have high [[volumetric efficiency]], the so-called "CV product", defined as the product of capacitance and voltage divided by volume.