Ciro Santilli @cirosantilli  40

Main implementations: the same as electronic switches: vacuum tubes in the past, and transistors in the second half of the 20th century.

The fundamental intuition about capacitors is that they never let electrons through.

They can only absorb electrons up to a certain point, but then the pushback becomes too strong, and current stops.

Therefore, they cannot conduct direct current long term.

For alternating current however, things are different, because in alternating current, electrons are just jiggling back and forward a little bit around a center point. So you can send alternating current power across a capacitor.

The key equation that relates Voltage to electric current in the capacitor is:So if a voltage Heavyside step function is applied what happens is:More realistically, one may consider the behavior or the series RC circuit to see what happens without infinities when a capacitor is involved as in the step response of the series RC circuit.

Ideally can be thought of as a one-way ticket gate that only lets electrons go in one direction with zero resistance! Real devices do have imperfections however, so there is some resistance.

First they were made out of vacuum tubes, but later semiconductor diodes were invented and became much more widespread.

Something where DC voltage comes in, and a periodic voltage comes out.

It resists to change in electric current. Well seen at: Video "LC circuit by Eugene Khutoryansky (2016)".