Understanding High Pass Filter: Plate Behavior and Phase Shift

[d.arbitman]

I'm having a hard time visualizing what happens on the plates of the capacitor in series with a resistor in a high pass filter circuit. When the input to the capacitor is high, assuming a sine wave (say +5V) what happens on the opposite plate of the capacitor (Vout)? Should the output follow the input (ie. is there no phase shift)?

 

[the_emi_guy]

d.arbitman
At frequencies much higher than the corner frequency, the output side of the capacitor will follow the input side with no phase difference (in the limit). Imagine a very rapid change of voltage on the input side of the capacitor. If the output did not follow this rapid change then we would have created a rapid change in voltage *across* the capacitor (dV/dt) which, in turn, would imply larger current (i = C dV/dt) than can be supported by the resistor.