A capacitor is constructed with plates of area A and separation s. The area between the plates is ?lled with a weakly ionized gas — a very poor conductive medium with resistivity = 10^8 ohms * cm. The density of the gas is so low that it has no e?ect on the capacitance, but this conductive path will discharge the capacitor just as e?ectively as an external resistor. What is the time constant of this circuit?