A parallel plate capacitor of plate area A and plate separation d is charged to a potential difference V and then the battery is disconnected. A slab of dielectric constant k is then inserted between the plates of the capacitor so as to fill the space between the plates. If Q, E and W denote respectively the charge on each plate, the electric field between the plates and the work done in the process of inserting the slab, then
A. `Q=(in_0AV)/(d)`
B. `Q=(in_0 kAV)/(d)`
C. `E=(V)/(kd)`
D. `W=(in_0 AV^2)/(2d)(1-(1)/(k))`
