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A water capacitor is a device that uses water as its dielectric insulating medium. Conventional capacitors use materials such as glass or ceramic as their insulating medium to store an electric charge. Water capacitors were created mainly as a novelty item or for laboratory experimentation, and can be made with simple materials. Water exhibits the quality of being self-healing; if there is a breakdown in the water, it quickly returns to its original and undamaged state. Other liquid insulators are prone to carbonization after breakdown and tend to lose their hold off strength over time. The drawback to using water is the short length of time it can hold off the voltage, typically in the microsecond to ten microsecond (us) range. Deionized water is relatively inexpensive and is environmentally safe. These characteristics along with the high dielectric constant make water an excellent choice for building large capacitors. If a way can be found to reliably increase the hold off time for a given field strength, then there will be more applications for water capacitors. 〔(【引用サイトリンク】first1=Magne )〕 Water has been shown not to be a very reliable substance to store electric charge long term, so more reliable materials are used for capacitors in industrial applications. However water has the advantage of being self healing after a breakdown, and if the water is steadily circulated through a de-ionizing resin and filters, then the loss resistance and dielectric behavior can be stabilized. Then in certain unusual situations such as the generation of extremely high voltage but very short, pulses a water capacitor may be a practical solution - such as in an experimental Xray pusler == History == Capacitors can originally be traced back to a device called a Leyden jar, created by the Dutch physicist Pieter van Musschenbroek. The Leyden jar consisted of a glass jar with tin foil layers on the inside and outside of the jar. A rod electrode was directly connected to the inlayer of foil by means of a small chain or wire. This device stored static electricity created when amber and wool where rubbed together.〔 *〕 Although the design and materials used in capacitors have changed greatly throughout history, the basic fundamentals remain the same. In general, capacitors are very simple electrical devices which can have many uses in today's technologically advanced world. A modern capacitor usually consists of two conducting plates sandwiched around an insulator. Electrical researcher Nicola Tesla described capacitors as the "electrical equivalent of dynamite".〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Water capacitor」の詳細全文を読む スポンサード リンク
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