A capacitor is a component that can store a voltage. To calculate the current that runs through a capactor you can use this formula:
Q = U x C
Witch results in:
 ( U/t is 'how fast the voltage changes')
C is the capacity of the capacitor, measured in Farad, so that 1C = 1F x 1V. 1 Farad is way to big to use, so people often work with micro Farads, nano Farads, and even pico Farads.
The formula shows that a uncharged capacitor does conduct current (when current runs through it the capacitor is charged, and U changes, so U is higher than 0). But a fully charged capacitor does not conduct current (U can't get bigger because it's already charged, so U is 0)
When you put two capacitors parallel you can see them as one if you add the capacities. You can easily imagine a capacitor by using the water analogy:
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| 'Empty' capacitor |
Charged capacitor |
The capacitor is a sphere with a bendable rubber wall in the middle. When the capacitor is charged (the wall is bend to one side) you can clearly see no current can run through it any more.
Electrolytic Capacitor
An electrolytic capacitor is a type of capacitor with a much larger capacity then a normal capacitor. A normal capacitor has a capacity of a few nano Farad, but an electrolytic capacitor can have a capacity up to 100 microFarad. Unlike a normal capacitor a electrolytic capacitor has a plus and a minus side, if you connect it in the opposite direction it can get defective. On a electrolytic capacitor the plus side is indicated with a dent. If the capacitor has two pins on the same site the minus site is the site with big minus symbols on it.
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Capacitor
Resistor color codes
