What is Capacitance of a Capacitor?

[turkey3_scratch]

What is it? Frankly I have no clue. I am not sure what it is a measurement of, or what importance it has when it comes to filtering ripple (talking about aluminum and polymer caps here, as in computer power supply units).

 

[Puff3r]

Long story short, it is the ability of a capacitor to store a charge. The power coming into the power supply must be converted from an analog wave to a digital signal ( think wave turning into a flat line here). This is done by using the discharge of a series of capacitors, diodes, and other components to store and release the charge in a semi stable flat line.

 

[turkey3_scratch]

Except a discharged capacitor has the same amount of charge as a charged capacitor, which is where my confusion comes into play. When a capacitor is energized, charge (particularly in this instance electrons) move from one plate to the other plate. When a charge enters plate A, a charge leaves plate B because the electric field reaches across the gap in the capacitor. In the end, the amount of stored charge in each plate changes, but the amount of charge for the entire capacitor remains exactly the same. It is the separation of positive and negative charge that allows the capacitor to store energy. One plate has an excess of protons, the other plate has an excess of electrons, which creates an extremely strong electric field to store energy in.

I had this discussion about a week ago actually on this forum. But once you find out that a discharged capacitor has as much charge as a charged capacitor, the idea of "capacitance" does not make sense, at least to me.

My source: http://amasci.com/emotor/cap1.html

 

[cosmoji]

the capacitance is how much electrical energy it can store. think of their function as being an overflow for the voltage so the voltage applied is steady even when it starts with fluctuations. thats how i picture it in my head. its not quite that simple, but thats really not something you're going to be using to decide on a purchase.

i'd start with finding one you like, and comparing it to this list. i would suggest staying in the top 2 tiers for a gaming rig, especially if you're going to be overclocking. they're higher end and will be using those fancy capacitors to control stuff like ripple.

 

[Puff3r]

And now I begin to wonder why I spent money on an EE degree...

Thanks for the link btw.

 

[turkey3_scratch]

And now I begin to wonder why I spent money on an EE degree...

Thanks for the link btw.

No problem 😀 I'm just a guy who knows a lot of misconceptions but doesn't know a whole lotta other stuff lol 😛

 

[turkey3_scratch]

the capacitance is how much electrical energy it can store. think of their function as being an overflow for the voltage so the voltage applied is steady even when it starts with fluctuations. thats how i picture it in my head. its not quite that simple, but thats really not something you're going to be using to decide on a purchase.

i'd start with finding one you like, and comparing it to this list. i would suggest staying in the top 2 tiers for a gaming rig, especially if you're going to be overclocking. they're higher end and will be using those fancy capacitors to control stuff like ripple.

I'm not looking into buying a power supplies - matter of fact I'm extremely well adept with computer power supply units. This question is merely for my own studies and curiosity. 😉

 

[TJ Hooker]

Ok, here's another way to think of capacitance: the ability of a capacitor to store energy in an electric field.

Capacitance relates to ripple suppression due to a capacitors tendency to resist changes in voltage by sinking or sourcing current. This is equivalent to sinking or sourcing energy (temporarily). The amount of energy that can be stored (and therefore the amount of energy that can be released) is governed by the capacitance.

 

[turkey3_scratch]

Thanks!