Capacitor, dielectric, conduction current, displacement current and flow of electrons

This diagram (in the video) shows a battery connected in series with a parallel-plate capacitor. The battery's positive terminal is connected to one plate, and its negative terminal is connected to the other plate. In a metallic wire or a metal capacitor plate, the movable charge carriers are electrons. When the battery is connected, its negative terminal pushes electrons away (repelling them) into the wire and toward the capacitor plate attached to it. Those excess electrons accumulate on that plate, making it negatively charged. Now, where do the positive charges come from? Here’s the subtle but crucial point: the battery doesn’t actually send “positive particles” to the other plate. Instead, when it pulls electrons off the plate connected to its positive terminal, that plate is left with a deficiency of electrons. The atoms in the metal still have their positively charged nuclei, but now there are fewer electrons than protons, so the plate as a whole becomes positively charged. The external wire provides the path, so electrons move around the circuit: leaving one capacitor plate and piling up on the other. Inside the dielectric, no electrons move — it’s an insulator. But the electric field across it forms instantly as soon as charge builds up on the plates. The dielectric itself doesn’t have free electrons to conduct current. However, its molecules are polarizable. The applied electric field slightly shifts the positive and negative parts of each molecule in opposite directions — this is called polarization. That internal rearrangement reduces the net field inside the dielectric and allows the capacitor to store more charge at the same voltage. So why current moves opposite direction of electron movement. When the idea of electric current was first defined (long before electrons were discovered), scientists simply decided that “current” would mean the flow of positive charge. That convention stuck. So by definition, conventional current flows in the direction a positive charge would move — from the battery’s positive terminal to its negative terminal. In other words, the direction of conventional current is opposite to the direction of actual electron motion.
In a capacitor, you have two metal plates separated by an insulating material (the dielectric). When you connect a battery, electrons start flowing in the external circuit — they pile up on the negative plate and are pulled off the positive plate. But inside the capacitor’s gap, the dielectric prevents electrons from actually crossing over. So how can we still talk about a current flowing through the whole circuit if the middle of it (the dielectric) blocks conduction? Even though no electrons move through the dielectric, something else changes inside it — the electric field. As charge accumulates on the plates, the field between them grows stronger. That changing electric field acts almost like a “bridge” that continues the effect of current through the gap. This idea is formalized in Maxwell’s equations, where he introduced a new term called the displacement current. It’s not a current of moving charges, but a current associated with a changing electric field. The dielectric + capacitor system isn’t just a classroom example — it’s one of the most essential components in every modern electrical and electronic device. Whether it’s stabilizing voltage, storing energy, tuning radio waves, or filtering noise, it’s always the same principle: energy stored in an electric field across a dielectric.