Capacitance

[davcro]

---

Members don't see this ad.

Question from BR:

"What happens over time to the capacitance of a capacitor, as the space between its plates is filled at a constant rate with a polar solution?"

My answer: The capacitance gradually decreases as the solution is added until the volume is completely filled, then the capacitance remains at the new value of k*Co

The answer key says the capacitance increases. Wouldn't a polar solution weaken the electric field between the places causing the capacitance to decrease?

 

[MedPR]

Sounds like this is a question about dielectrics, which increase capacitance.

 

[qtsjoe]

I would of reasoned polar solutions implies electroytes therefore, since capacitance is the ability to store charge...I would think the solution would act as an extra storage of charge....

 

[MedPR]

It increases capacitance by making it easier for charge to accumulate on the two capacitor plates. Once the charge on the capacitor plates builds up to a point where it is no longer energetically favorable to add more charge, it has reached its capacity. You can decrease the amount of energy needed to add a charge to the plate by putting a dielectric in the middle of the capacitor plates. The dielectric is polarizable and orients itself within the electric field in a manner that allows it to pull the charge on both capacitor plates towards it. So imagine a negative point charge on a plate. With a dielectric, that negative point charge will be attracted to a positive charge (on the dielectric). This makes it easier to add another negative charge to the plate.

 

[davcro]

It increases capacitance by making it easier for charge to accumulate on the two capacitor plates. Once the charge on the capacitor plates builds up to a point where it is no longer energetically favorable to add more charge, it has reached its capacity. You can decrease the amount of energy needed to add a charge to the plate by putting a dielectric in the middle of the capacitor plates. The dielectric is polarizable and orients itself within the electric field in a manner that allows it to pull the charge on both capacitor plates towards it. So imagine a negative point charge on a plate. With a dielectric, that negative point charge will be attracted to a positive charge (on the dielectric). This makes it easier to add another negative charge to the plate.

Got it, thanks!