A zener diode is a diode that allows electrons not only to pass from anode to cathode, but also cathode to anode. Now, that might sound like a wire, but it’s not. It only lets electrons pass through the reverse bias at a certain point, known as the breakdown voltage. How does it work? As weird as it sounds, electrons “Teleport” through the diode. It is called “Quantum Tunneling”. Electrons are so small they can pass through a barrier, like the cathode. Its neat stuff.
