# Two metal plates form a parallel plate capacitor. The distance between the plates is given as ‘d’. A metal plate of thickness (d/2), and two dielectric slabs of thickness (d/4) is introduced between the plates as shown in the figure. If the metal plate is removed find the work done in slowly removing it. (The plates of capacitor is connected to a battery having potential difference ‘v’)

$\large\frac{4A \in_0 v^2k_1^2k_2^2}{d(k_1+k_2)(k_1+k_2+2k_1k_2)}$