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capacitor polarity

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normad

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hey, can someone please explain to me how capacitor polarity matter when its used as a bypass capacitor to remove a DC offset? i dont understand how capacitors are polarized in the first place

thanks :)
 
IT's very simple. The cap may start leak or worse, it can explode if applied negative voltage.

I'm sorry I cannot explain in more detail, because I don't remember the exact physics behind a polarized cap.
 
It doesn't matter, you can use a non-polarised capacitor if you like, but it'll be much more expensive.

There's a good article on electrolytic capacitors on Wikipedia.

It's possible for old electrolytics, which haven't been used for many years, to become depolarised, in which case they need repolarising which is as simple as applying the power slowly raming up the voltage.
 
Polarized capacitors are only one of the parts that exist. They exist because it is a good, cheap method to make a capacitor that has lots of capacity and can be made to high voltage abilities. Their rule is to only put a positive potential on the side marked positive because the chemicals inside only plate the aluminum on one side.

How does it matter that there is a polarity rule about polarized capacitors? Because that's the way they work. Same as rule about polarity of diodes.
 
An electrolytic capacitor behaves like a diode. It has a near infinite resistance in one direction and a fairly low resistance in the other direction. The polarity indicator marks the way to install it so it operates in the high resistance mode. If you reverse it, current flows through it and causes a great deal of power to be dissipated within it. That much power will cause the electrolyte to boil causing a steam explosion that can be quite devastating if you happen to be too close to it when it blows. The same thing will happen if you exceed the rated WVDC.
 
i dont understand how capacitors are polarized in the first place
Polarized capacitors are not a particularly desired type of capacitor, there's no circuit advantage to being polarized. It's just that the chemistry of large (electrolytic) capacitors is such as to make a capacitor that can tolerate voltage in only one direction.
 
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