17. Capacitor and dielectric slab. Consider (see Figure 3.) a capacitor with a fixed charge Q but without adielectric slab (vacuum permittivity is ε0). Its energy is denoted as U0 . A dielectric slab of dielectricconstant K(i.e, permittivity becomesKε0) is now inserted into the plates. Find the work W requiredto insert the dielectric between the plates.

(A) 
(B) W=U0(K+1)
(C) 
(D) 