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A diode is a two-terminal component in electronics with a unidirectional flow of current. It offers low resistance in the direction of current flow and offers high resistance in the opposite direction. Diodes are mostly used to prevent damage to components, especially due to electromotive force in circuits which are usually polarized.
The two terminals of a diode are polarized, with the positive end called an anode and the negative end called a cathode. The cathode is usually silver or has a color band. Control of current flow direction is one of the key features of diodes — the current in a diode flows from anode to cathode. The behavior of a diode is similar to the behavior of a check valve. One of the most important characteristics of a diode is the non-linear current voltage. If higher voltage is connected to the anode, then current flows from anode to cathode, and the process is known as forward bias. However, if the higher voltage is connected to the cathode, then the diode does not conduct electricity, and the process is called reverse bias.
There are different types of diodes such as normal diodes, light-emitting diodes, zener diodes, Schottky diodes and photodiodes. The circuit symbol of a standard diode is triangle with one corner against a vertical line.
Diodes have a wide range of applications, such as being used in: