A dialectic of width d is inserted into a capacitor made up of two plates, with the plates being a distance D apart. D>d. Afterwards, the capacitor acts like it is two capacitor connected in series. Why? I mean how the heck is the dialectic supposed to get induced charges equivalent to the ones on the capacitor-plates? the situation is illustrated in the solution manual. Look for assignment 4b ("Oppgave 4 b", page 4) http://folk.ntnu.no/sveinoll/ov/TFY/4155%20Elektrisitet%20og%20Elektromagnetisme/V11/LF/Ov06los.pdf [Broken]. The situation as described is like A, and the capacitor acts like in B.