Question

A 100 μF parallel plate capacitor having plate separation of 4 mm is charged by 200 V dc. The source is now disconnected. When the distance between the plates is doubled and a dielectric slab of thickness 4 mm. and dielectric constant 5 is introduced between the plates, how will (i) it capacitance, (ii) the electric field between the plates, and (iii) energy density of the capacitor get affected ? Justify your answer in each case. 

Answer 1

(ii) Charge on capacitor plates, when 200 V p.d is applied, becomes 

Even after the battery is removed, the charge of 2 x 10^-2 on the capacitor plates remains the same. 

Comments

Why you didn't put value of dielectric constant in calculation of energy density