A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant k, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
A. the potential difference between the plates decreases k times
B. the energy stored in the capacitor decreases k times
C. the change in energy stored is `(1)/(2)CV^2((1)/(k)-1)`
D. the charge on the capacitor is not conserved
