Say you are using an op-amp as a buffer, so the output is tied straight back to the inverting input. And in-between your voltage source and the non-inverting input you have a capacitor. (Voltage Source)---------------||-------------(Non-inverting input of the op amp) How would the op-amp know if there was an AC voltage source? There isn't a way for charge to accumulate on the other side of the capacitor, so no voltage will be detected at the input, right? Or would the charge just become displaced in the second leg of the capacitor almost like an antenna? If so, what are the equations for such situation? Even though there is charge being displaced, I'd imagine the detected voltage at the input would still be considerably smaller than the voltage source, right?