This is where the capacitance (farads) of a capacitor comes into play, which tells you the maximum amount of charge the cap can store. There are enough negative charges on one plate that they can repel any others that try to join. A capacitor can retain its electric field - hold its charge - because the positive and negative charges on each of the plates attract each other but never reach each other.Īt some point the capacitor plates will be so full of charges that they just can't accept any more. When positive and negative charges coalesce on the capacitor plates, the capacitor becomes charged. When charges group together on a capacitor like this, the cap is storing electric energy just as a battery might store chemical energy. The stationary charges on these plates create an electric field, which influence electric potential energy and voltage. But, with the dielectric sitting between them, as much as they want to come together, the charges will forever be stuck on the plate (until they have somewhere else to go). The positive and negative charges on each of these plates attract each other, because that's what opposite charges do. When you get into the farad to kilofarad range of capacitance, you start talking about special caps called super or ultra-capacitors. Usually you'll see capacitors rated in the pico- (10 -12) to microfarad (10 -6) range. It turns out that a farad is a lot of capacitance, even 0.001F (1 milifarad - 1mF) is a big capacitor. The standard unit of capacitance is called the farad, which is abbreviated F. The capacitance of a capacitor tells you how much charge it can store, more capacitance means more capacity to store charge. Each capacitor is built to have a specific amount of capacitance. The value should indicate the capacitance of the capacitor how many farads it has. More on that in the types of capacitors section of this tutorial.Įach capacitor should be accompanied by a name - C1, C2, etc. The symbol with the curved line (#2 in the photo above) indicates that the capacitor is polarized, meaning it's probably an electrolytic capacitor. (3) is an example of capacitors symbols in action in a voltage regulator circuit. (1) and (2) are standard capacitor circuit symbols.
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