1) When we insert dielectric between plates, plates can "hold" a greater quantity of charge since capacitance is increased. But when capacitance increases, does it require that voltage decreases? (From the formula C = Q/V, capacitance and charge could increase while voltage remains constant.) But voltage V = PE/Q. If Q increases due to greater capacitance, then voltage would have to decrease. But in a given circuit, if the voltage source remains the same before and after inserting the dielectric, I don't understand how the voltage could change. 2) Also, why is the "ground," as a generality, considered less resistant than other materials. How are we sure of this? For instance, when using a defibrillator, administrators need to elevate the patient off the ground lest the current "skip" the patients' heart. But why is the ground's resistivity invariably so low compared to human body's, building materials of a house? Thanks for helping to clarify.