>They resist standard DC... but what about AC at a certain frequency, or pulsed DC at a certain frequency?
Um.. yes. This is actually exactly how you model coupling capacitors when analyzing circuits. You use them to connect two nodes. Apply DC and no current flows through once the capacitor is charged. Apply AC and the signal is transmitted to the other side. The strength of the transmitted signal is dependent on frequency and of course whatever else you have connected to the circuit.
Um.. yes. This is actually exactly how you model coupling capacitors when analyzing circuits. You use them to connect two nodes. Apply DC and no current flows through once the capacitor is charged. Apply AC and the signal is transmitted to the other side. The strength of the transmitted signal is dependent on frequency and of course whatever else you have connected to the circuit.