Two parallel-plate capacitors have the same separation and plate area. The capacitance of each is initially 10 μF. When a dielectric is inserted such that it completely fills the space between the plates of one of the capacitors, the capacitance of that capacitor increases to 35 μF. The 35- and 10-μF capacitors are connected in parallel and are charged to a potential difference of 100 V. The voltage source is then disconnected.

(a) What is the stored energy of this system?

(b) What are the charges on the two capacitors?

(c) The dielectric is removed from the capacitor. What are the new charges on the plates of the capacitors?

(d) What is the final stored energy of the system?