What does a diode do in a circuit?

A diode allows current to flow in only one direction, which is its fundamental characteristic. This occurs due to its semiconductor material structure, typically made from silicon or germanium. When the diode is forward-biased, meaning the positive side of the voltage is connected to the anode and the negative to the cathode, it allows current to pass through. In reverse bias, where the anode is more negative than the cathode, the diode effectively blocks current, thus preventing it from flowing.

This unidirectional flow of current is essential in various applications, such as rectifying alternating current (AC) to direct current (DC), protecting circuits by preventing backflow of current, and in signal demodulation. The unique property of diodes makes them key components in power supplies, signal processors, and many other electronic applications, fulfilling critical roles that would not be possible in circuits if current could flow in both directions.