Capacitor +ve & -ve

Thread Starter

aamirali

Joined Feb 2, 2012
412
1. What if +ve terminal of voltage is applied to negative plate of cap & -ve terminla is connected to +ve plate of cap. Cap is electrolytic.

2. What is it which make separate +ve & -ve plate in electrrlytic capacitor while in ceramic plates can be interchanged
 

bretm

Joined Feb 6, 2012
152
The dialectric in an electrolytic capacitor is a thin layer of metal oxide formed on the plate surface by current-driven chemical reaction. With forward current it's somewhat self-repairing, but with reverse current the reaction is reversed and the oxide layer degrades, which allows current to leak through, which accelerates the reaction making it degrade faster, etc. Desctruction happens quickly.
 

Thread Starter

aamirali

Joined Feb 2, 2012
412
Cap will break even if reverse voltage is less than breakdown voltage.
If yes, If I have a ac source & put a cap across it then will it break on -ve cycle of capacitor?????????
 

WBahn

Joined Mar 31, 2012
25,104
Cap will break even if reverse voltage is less than breakdown voltage.
If yes, If I have a ac source & put a cap across it then will it break on -ve cycle of capacitor?????????
The breakdown voltage for a polarized capacitor is the FORWARD breakdown voltage. Unless the specific device is spec'ed otherwise, you need to assume that there is NO reverse breakdown voltage (or, more to the point, that ANY reverse voltage will cause breakdown).
 
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