Thus, the capacitance increases. If a dielectric fills the space between the two plates, the capacitance increases by a constant, k . We call this constant the dielectric constant . Because the charge on a capacitor does not change with the insertion of a dielectric, the voltage drop across the capacitor must decrease. If the field strength of a medium exceeds the dielectric strength, then the insulating properties will break down and the medium will then begin to conduct.
Most insulating materials have dielectric strengths greater than air's .
A dielectric increases the capacitance of a capacitor. A dielectric increases the maximum operating voltage of a capacitor. A dielectric may provide mechanical support between the conducting plates. According to the formula for the energy of a capacitor, one can also see that this energy decreases when a dielectric is inserted between the plates of a capacitor. Problems with Dielectrics 1.