A parallel-plate capacitor of capacitance 150pF is connected to a 400V battery and fully charged. The battery is then disconnected, leaving the capacitor isolated.
a. (i) Find the charge stored on the capacitor immediately after disconnection from the battery.
b. (ii) A dielectric slab of relative permittivity 3 is now completely inserted between the plates. Determine the new capacitance of the system.
c. (iii) Calculate the new potential difference across the plates after the slab is inserted.
d. (iv) Compute the energy stored in the capacitor before and after the insertion of the dielectric, and comment on the change in energy.