Difference between polarized and non polarized capacitors

[hisham.i]

Hello,

I googled the difference between polarized and non polarized capacitors and all i found was differences in construction and the material that they are formed from.

I want to know why there is 2 types of capacitors, what are the differences (cost, technical, etc), why there is not only non polarized?

thanks

 

[Runei]

Non-polarized capacitors (the ones we learn about in physics at first), at hard to manufacture at a small size compared to their capacitance (they become very big if we want a big capacitance). Also, they can be quite expensive when they become bigger.

Polarized capacitors give us a way to manufacture smaller capacitors, but with a high capacitance. The drawback however, is that they are polarized.

Some places with high requirements, it is not allowed to use polarized capacitors.

 

[NascentOxygen]

Electrolytic capacitors are a way to manufacture a high capacitance relatively cheaply and in a small sized package. They are definitely a compromise, and have a finite life.

You can connect two electrolytic capacitors back-to-back (electrically) so as to form a non-polarized electrolytic capacitor. Obviously, it will be about 4 times the cost of a single polarized capacitor giving the same capacitance.

 

[jim hardy]

The answer to your question is:
Electrolytic capacitors pack thousands of times more capacitance into a given volume than you can get with film dielectric types.
But - electrolytic capacitors are necessarily polarized because of how they're made..

capacitance= area / distance.

Area is the area of the foil

Etching an aluminum foil gives it more surface area per square inch. The microscopic hills and valleys have more surface area than would a mirror flat sheet. Remember the old saying "Colorado would be bigger than Texas if you ironed it flat" ?
Etching gives a large [STRIKE]denominator [/STRIKE] NUMERATOR (golly I'm doing everything backward today !)
Distance is the thickness of the dielectric.

In electrolytics the dielectric is not a plastic or paper film but a thin layer of aluminum oxide on one the aluminum sheets. It's only a few atoms thick so you have a very small denominator.
This little paper by Cornell-Dubelier explains it well.

http://electrochem.cwru.edu/encycl/misc/c04-appguide.pdf

old jim

 

[alphy]

for your help

There are two main types of capacitors: polarized and non-polarized. The main difference between these two types lies in the materials used to construct them and their ability to handle direct current (DC) and alternating current (AC) signals.

Polarized capacitors, also known as electrolytic capacitors, are made with a dielectric material that is coated with an electrolyte solution. This allows them to store large amounts of charge and handle high voltages, making them ideal for use in power supply circuits. However, they can only be used with DC signals, as the electrolyte solution is not stable enough to handle AC signals.

On the other hand, non-polarized capacitors, also known as ceramic or film capacitors, are made with a non-polar dielectric material, such as ceramic or plastic. This allows them to be used with both AC and DC signals, making them more versatile than polarized capacitors. However, they have a lower capacitance and can only handle lower voltages, making them more suitable for use in low power circuits.

The differences in cost and technical specifications between polarized and non-polarized capacitors are largely due to their different construction materials and capabilities. Polarized capacitors tend to be more expensive and have higher capacitance and voltage ratings, while non-polarized capacitors are more affordable but have lower capacitance and voltage ratings.

As for why there are two types of capacitors, it ultimately comes down to their specific applications. Polarized capacitors are necessary for certain circuits that require high capacitance and voltage handling, while non-polarized capacitors are more suitable for general use in low power circuits. Having both types allows for more flexibility in circuit design and ensures that the correct type of capacitor is used for each specific application.