When you insert a dielectric material (like glass) between the plates, the permittivity ε increases because the dielectric constant k of glass is greater than that of air or vacuum. The new capacitance when a dielectric is inserted is given C′ = \(\frac{\text{kεoA}}{\text{d}}\) where k is the dielectric constant of the glass, and ε\(_0\) is the permittivity of free space. Since k >1 for glass, inserting it increases the capacitance: C ′ = kC Thus, with the glass block inserted, the capacitance C′ will be greater than the original capacitance C.