[susus]

A parallel plates capacitor is connected to a battery with emf 13.0 V. The width of the plates is 4.0 cm, the length is 5 cm. And the distance between two plates is 0.005 mm (the distance is much less than the width and the length, it means that edge effects is negligible), as shown below. Firstly, the capacitor is filled with a block of dielectric with a dielectric constant egw = 4.42E-11. Find: when the dielectric is pulled out to a position, remaining half long in the capacitor, what's the electric force acting on the dielectric?