甚麼是電容器

光管電容 = 舊款光管多有一個電流鎮流器，係由一個鐵芯加上銅線圈，由於鎮流器線圈會導致電流延遲而功率因數降低再產生大電流，為佐要提高功率因數所以要加一個電容，通常呢個電容係並聯盞燈既線路，所以電容電壓就係電源電壓，為佐安全起見，通常會預多10%即250V
冷氣電容 = 有分摩打起動電容及運行電容兩種，摩打起動電容淨係摩打起動時用到，運行時就隔離，摩打運行電容就一開機就用到関機，作用係將電源相位改變來推動架摩打，通常起動電容既電壓同電源電壓一樣，但係有 D 人設計用半電壓即 110V，運行電容因爲長時間推動架摩打，需要設計用到 1.732 倍，即係 380V。

2008-08-27 08:26:48 補充：
電流鎮流器 = 火牛

不明白

電容器 = capacitor
A capacitor is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. Capacitors are often used in electric and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters. Practical capacitors have series resistance, internal leakage of charge, series inductance and other non-ideal properties not found in a theoretical, ideal, capacitor. The impedance is analogous to the resistance of a resistor. The impedance of a capacitor is inversely proportional to the frequency - that is, for very high-frequency alternating currents the reactance approaches zero - so that a capacitor is nearly a short circuit to a very high frequency AC source. Conversely, for very low frequency alternating currents, the reactance increases without bound so that a capacitor is nearly an open circuit to a very low frequency AC source. This frequency dependent behaviour accounts for most uses of the capacitor (see "Applications", below). Reactance is so called because the capacitor does not dissipate power, but merely stores energy. In electrical circuits, as in mechanics, there are two types of load, resistive and reactive. Resistive loads (analogous to an object sliding on a rough surface) dissipate the energy delivered by the circuit as heat, while reactive loads (analogous to a spring or frictionless moving object) store this energy, ultimately delivering the energy back to the circuit. Also significant is that the impedance is inversely proportional to the capacitance, unlike resistors and inductors for which impedances are linearly proportional to resistance and inductance respectively.