Why do capacitors with different capacitance values have different uses?

[fluidistic]

If you can get any difference of potential across a capacitor of any capacitance, why it's better to use capacitors with small capacitance in some cases and capacitors with a big capacitance in other cases?

 

[timthereaper]

I would think it has to do with the amount of charge able to be stored in the capacitor and maybe the rate at which it discharges in an RC or RLC circuit.

 

[fluidistic]

I would think it has to do with the amount of charge able to be stored in the capacitor and maybe the rate at which it discharges in an RC or RLC circuit.

If there is a limited amount of charge being able to be stored within the capacitor, it means there is also a limit of the difference of potential across it.
Then I have some questions arising from this fact.
In an RC series circuit, imagine there's an emf of 1000 V and the capacitor has its maximum voltage, namely 500 V. Will there be any current in the circuit?
Does the maximum voltage across the capacitor mean it's fully charged?

 

[nasu]

If you can get any difference of potential across a capacitor of any capacitance, why it's better to use capacitors with small capacitance in some cases and capacitors with a big capacitance in other cases?

You actually cannot. The maximum voltage depends on the distance between plates and the value of the electric breakdown field of the dielectric.
The maximum voltage is given by V_max=E_breakdown * d.
If you go over this you will get a discharge through the dielectric and ruin the capacitor (and maybe the circuit).
The voltage indicated on the capacitor may be less than this maximum value, to allow for some safety factor.

The capacitance used in a given circuit may depend less on how much charge you can store but rather on time constant desired for discharge or for oscillating processes. In filters the capacitance determines the filter parameters, and so on.

 

[Gordianus]

I'd suggest reading about time constants and/or cut-off frequencies

 

[fluidistic]

Ok thank you guys!
So I'm left with the questions of post #3.

 

[AlephZero]

In an RC series circuit, imagine there's an emf of 1000 V and the capacitor has its maximum voltage, namely 500 V. Will there be any current in the circuit?

Yes, the current will be (1000-500)/R

Does the maximum voltage across the capacitor mean it's fully charged?

The capacitor doesn't "know" anything about a maximum voltage, or being fully charged. "Maximum voltage" just means the voltage that the capacitor is designed to withstand without failing.

In your RC circuit, the voltage across the capacitor will keep rising towards 1000V until something stops it, and that "something" might be the capacitor self-destructing. Or the capacitor might work properly at twice its "maximum" voltage for longer than it takes for you to do the experiment - though it is a bad idea to design electronic circuits that deliberately take components outside of their designed operating conditions.

 

[fluidistic]

Thank you very much AlephZero. I understand much better now.