I have a doubt about a couple of exercises tha asks to find the work done on introducing a dieletric between the plates of a capacitor. Yes, this question is in the general case, how do we procede? I really don't know how to start those questions. I know how to find the new capacitance, the new field between the plates and the new voltage, but I don't know how to find the work required to introduce the dieletric.
So, given a capacitor of capacitance $C$ and charge $Q$ what's the procedure if we want to find the work on introducing a dieletric of constant $k$ inside the plates?
I just want some ideas on how to start those problems.
Thanks very much in advance.