Capacitance and Electric Field

[EnchantedEggs]

I've gotten myself in a bit of a muddle here, I'm hoping you lovelies can help me out!

So, the capacitance relates to the amount of charge a capacitor can store. Higher capacitance, greater charge. Greater stored charge, greater stored energy (right? or not?).

So a higher capacitance means you can store more energy in that capacitor. In order to increase the capacitance, we can insert a dielectric between the plates. This lowers the electric field between the plates and increases the capacitance.

If this is so, then a lower electric field results in a greater capacity to store energy? I must have gone wrong somewhere - I thought the whole point is that we're using an electric field to store potential energy. So surely a lower field means less stored energy? Argh!

Can someone clarify my muddled thinking a bit? I've been looking at articles and equations for hours now and I just seem to be making myself even more confused.

 

[willem2]

It makes a difference whether the capacitor is connected to a battery, so the potential difference across it is constant, so the electric field will also be constant, or whether it is unconnected, so the electric charge is constant.