What happens to capacitance and voltage when a battery is disconnected?

[FahimP]

hello i need some explanation on this .
I know that when a battery is connected it provides constant voltage across the capacitors. But the happens when the battery is disconnected. What happens to the voltage, the capicitance, and what is the importance of dielectric.

I have read the book the researched online but i can't seem to find an explanation on what happens when the battery is connected and when it is disconnected. PLEASE HELP

 

[cragar]

When you charge up a capacitor and then disconnect the battery the charge is stuck on the plates . So if i increase the distance between the plates the voltage will go up. V=Ed
Because the electric field is constant between the plates . And the capacitance is only a function of geometry of the plates . And the dielectric allows more charge to be stored on the plates, and also so the plates don't touch each other.

 

[cragar]

In a parallel plate capacitor setup , If the distance is not to large the E field remains constant . I have a question for you, how do you find the electric field between the plates and the answer does not even have distance in it.

 

[cragar]

Suppose the plates where infinite, do you still think that the E field will fall off, or do you think it would be constant between the plates.

 

[cragar]

watch this video , Prof lewin explains capacitors and does a demo that shows the voltage will increase when you separate the plates. The E field is constant between the plates .
Start at about the 22min mark.

 

[cragar]

No problem , I've been wrong many times, And its a very strange concept .