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Direct current was used originally for electric power transmission after the development by Thomas Edison of the commercial generation of electricity in the late nineteenth century. It has mostly been abandoned for this purpose in favor of alternating current (discovered and promoted by Nikola Tesla, see War of Currents), which is much more suited to transmission over long distances. DC power transmission is still used to link AC power networks with different frequencies.
DC is commonly found in many low- voltage applications, especially where these are powered by batteries, which can only produce DC. Most automotive applications use DC although the generator is an AC device which uses a rectifier to produce DC. Most electronic circuits require a DC power supply. Although DC stands for 'Direct Current', DC is generically used to refer to constant polarity voltages. Some forms of DC vary wildly in voltage, such as the raw output of a rectifier. Running them through an RC low-pass filter will produce more stable voltage.
Direct current installations usually have different types of socketA socket generally designates a cavity or region used for fitting and connecting some specific device. Physical sockets Electrical sockets A CPU socket is a physical and electrical specification of how to connect a CPU to a motherboard. In electronics, as, switchThis article is about electrical switches. For other meanings of the word "switch", see Switch (disambiguation). A switch is a device for making or breaking an electric circuit, or for selecting between multiple circuits. In the simplest case, a switch haes, and fixture s, mostly due to the very low voltages used, from those suitable for alternating current. It is usually extremely important with a direct current appliance to not reverse polarity unless the device has a diode bridgeA diode bridge is an electronic circuit that provides the same polarity of output voltage and current for both possible polarities of input power. When used in its most common application, for conversion of alternating current (AC) input power into direct to correct for this. (Most battery-powered devices don't.) There is currently ( 2000This page is about the year 2000. See 2000 AD for the UK comic book, Number 2000 for other uses. 2000 is a leap year starting on Saturday (see link for calendar), and also the International Year for a Culture of Peace''. Events Y2K passes without the seri) some interest in High Voltage Direct Current ( HVDC) transmission systems. DC is also used in solar powerSolar power describes a number of methods of harnessing energy from the light of the sun. It has been present in many traditional building methods for centuries but has become of increasing interest in developed countries as other power sources such as fo systems that are supplied by solar cellA solar cell a form of photovoltaic cell is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). Solar cells are used to power many kinds of equipment, including satellites, calculators, rems.