Diode (Encyclopedia of Science)
A diode is an electronic device that has two electrodes (conductors of electrical currents) arranged in such a way that electrons (subatomic particle having a negative charge) can flow in only one direction. Because of this ability to control the flow of electrons, a diode is commonly used as a rectifier device that converts alternating current into direct current. (Alternating current is an electric current that flows first in one direction and then in the other. But alternating current fed into a diode can move in one direction only, thereby converting the current to a one-way flow known as a direct current.)
Types of diodes
In general, two types of diodes exist. Older diodes were vacuum tubes containing two metal components, while newer diodes are solid-state devices consisting of one n-type and one p-type semiconductor. (Solid-state devices are electronic devices that take advantage of the special conducting properties of solids. Semiconductors are substances that conduct an electric current but do so very poorly.)
Vacuum tube diode. The working element in a vacuum tube diode is a metal wire or cylinder known as the cathode. Surrounding the cathode or placed at some distance from it is a metal plate. The cathode and plate are sealed inside a glass tube from which all air is removed. The cathode is also attached to a heater which,...
(The entire section is 410 words.)
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