The force can be screened by the ions as they will generate an opposite field that tries to cancel the original field... A dielectric will reduce this force too, according to its dielectric constant...
If you insert a dielectric in a charged capacitor its voltage drops and the electric field become weaker by k dielectric constant.
50kv mm is the same as 50MegaVolts/meter or 50 million newtons per coulomb...
Question once you charge your capacitor, and disconnect it from source, assuming its ideal, how can you consume this potential energy? No way bro
You can only add other sets of charges internally in such way that the potential is diminished for say or increased,, externally things can be done to increase or to decrease it inside but actually what happens is that if you add another layer with opposite charges outside separated by another dielectric than the electric fields internally can be reduce to zero ... equilibrium rocks... but the charges on the outside plates will point electric fields outside the capacitor...
In a two plate capacitor ideally theres no external field!
I mean you get to capacitors one inside the other, you charge the outside capacitor and disconnect it, than you charge the inner capacitor with opposite polarity with the same charge that is at the outside plates. the charges of the outer plates now will point electric fields out of the capacitor...