What is direct current?
912115
current that flows in one direction as opposed to alternating current, which flows back and frth.
866700
electricity produced due to flow of charges/electrons
34593
... or to use the hydraulic analogy, current is how much water (electrons) is flowing through the pipe.  Voltage is the water pressure.
1052197
A volt is a unit of, essentially, electric force. It basically measures how much crud a particular current can go through before it weakens too much. It serves its purpose in that it both allows us to build good transformers and provides another way to transmit huge amounts of power without heating up the wires. It's named after Volta, the sci guy who made the first voltaic pile.
119408
there where a time when engineers/scientist thought of a conventional current flow in which the current flows from the postive to the negative. that time diodes are in existence. through times, they found out that current really flows in opposite directions, that is from negative side to positive side that is the electron flows. and since diodes are in existence they just make a vertical lines in an arrow to represent that the current flows in the other side...
118492
AC is when the current alternates, thus the term Alternating Current. DC is Direct Current where the electron stream does not change directions.
31337
It is DC voltage.\n\nhttp://www.ecs.umass.edu/ece/allerton/papers1999/36/
374690
DC is Direct Current in which the electrons move in one direction through the wire all the time.\nAC is Alternating Current in which the electrons flow one way for a short time and then switch directions and flow the other way for a while.\nThe constant direction switching does not interfere with the work the electricity does if the devices using it are properly designed. Some devices, like incandescent light bulbs, work equally well with either type of current. Other types of devices, like transformers, depend on the constant switching to operate.
808466
electric induction is the induction of current...\nyou can induce current by have a coil with current i, and a magnet...\nthe magnet may be the one moving forth and back or the current-carrying coil, or both...\nac dynamo is what makes current alternating.... or changing in direction... unlike dc....\nwhen dc makes dynamos mechanically usable, dynamos are used make ac...
251203
Electricity. It's everywhere. It's in your house, in the computer on which you are reading this, in the air, in your body, blah blah blah. You get the point. It also plays an important integral part of sound systems. From the microphone to the loudspeaker, everything is electrical, and you need to know a few things about it.\n\n\nANYONE FOR FROGS' LEGS?\n\nAn Italian scientist named Alessandro Volta did experiments with electric charge back in the 1800s; he managed to make dead frogs (yes, frogs) "move" by using them as part of an electrical circuit, and is credited with providing us with a lot of information about electric potential. The volt was thus born. Voltage is defined as the electric charge between two points. In household terms, voltage is akin to water pressure available to do work. It can't do any work until a circuit (the plumbing and a water tap) is complete so that current (the amount of water) can flow. In engineering terms, voltage is the potential energy of a bunch of electrons. Current, measured in Amperes, is the flow of electric charge; we can say that current is the rate of flow of electrons, but technically it is the opposite flow that we call current-- as electrons move in one direction, holes are left behind, and appear to flow in the opposite direction. We should also remember from our physics classes that there is a fundamental equation used in electricity: Ohm's Law.\n\n\nOHM SWEET OHM\n\nOhm's Law is the mathematical relationship between voltage, current and resistance. It is named after George Ohm, its founder. Ohm's Law states that the current in a conductor is directly proportional to the voltage across it, and inversely proprtional to its resistance. In simpler terms, the law states that more voltage will produce more current if resistance stays the same, but higher resistance will cause the current to decrease if the voltage stays the same. In our household plumbing example, we can say that Ohm's Law dictates that more water pressure will produce more output if the diameter of the pipe stays the same, but a smaller-diameter pipe will cause the output to decrease if the water pressure stays the same.\n\nWith these three basic components, we have electricity. Current is "drawn" from a power supply due to the presence of a voltage placed across a load, or resistance. For instance, a typical electrical outlet has 120 volt potential (pressure- it has the capacity to give you 120 volts), but nothing is connected. If you put some load across its terminals, like a lightbulb or steam iron, you then have a complete circuit in which electrical current can flow. As we said before, a higher resistance will yield less current than low resistance. A direct short will cause a very large flow of current, because there is no resistance. If the supply is capable of delivering enough current, it is likely that the wire will eventually heat up and melt. This is why circuit-breakers and fuses are used. They limit current flow by opening (as opposed to shorting) a circuit before current flow becomes too large-- a 15A circuit-breaker will trip when the loads connected to that circuit try to pull more than 15A of current.\n\nMakes sense, right? Good. Ohm's Law is represented as the rate of flow of electrons, and voltage is represented as the electric charge between two points.\n\nOhm's Law:V = I x R, where V = Voltage, I = Current, and R = Resistance. \n\nHELL'S BELLS\n\nElectricity appears in two forms: alternating current (AC) and direct current (DC). Direct current does not change directions-- the electron flow is always from the negative pole to the positive pole-- although as we mentioned before, the electrons themselves don't really "move," it's the holes that are created that "move." Direct current is almost always what is used inside of electronic devices to power the various internal components, but it is a harmful thi
724440
It means Alternate Current/Direct Current for forms of electrical input and output. AC/DC also is slang for bi-sexual orientation in people, having the desire and capacity to go either way with sexual partners.
183672
A semiconductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current. Its conductance varies depending on the current or voltage applied to a control electrode, or on the intensity of irradiation by infrared (IR), visible light, ultraviolet (UV), or X rays. \nThe specific properties of a semiconductor depend on the impurities, or dopants, added to it. An N-type semiconductor carries current mainly in the form of negatively-charged electrons, in a manner similar to the conduction of current in a wire. A P-type semiconductor carries current predominantly as electron deficiencies called holes. A hole has a positive electric charge, equal and opposite to the charge on an electron. In a semiconductor material, the flow of holes occurs in a direction opposite to the flow of electrons.\n\nElemental semiconductors include antimony, arsenic, boron, carbon, germanium, selenium, silicon, sulfur, and tellurium. silicon is the best-known of these, forming the basis of most integrated circuits (ICs). Common semiconductor compounds include gallium arsenide, indium antimonide, and the oxides of most metals. Of these, gallium arsenide (GaAs) is widely used in low-noise, high-gain, weak-signal amplifying devices.\n\nA semiconductor device can perform the function of a vacuum tube having hundreds of times its volume. A single integrated circuit (IC), such as a microprocessor chip, can do the work of a set of vacuum tubes that would fill a large building and require its own electric generating plant.
301222
Voltage is the parameter of electricity which causes current to flow when a circuit is completed. Voltage is always presented in an energized line, whether or not the circuit is complete. When the circit is complete, we say that electricity is flowing.\n\nHence, it is said that a cell is an electrictiy generating device.
268227
Power is directly related to amperage by the voltage, P=I*V.
789048
It is linear because the current and voltage relationship can be described as a linear differential equation:\n\nI = dQ/dt = C * dV/dt
231801
The first 5 leters of the word electricity come from the word 'electron'. In the study of electricity (or electical engineering if you like), 2 quantities help us understand how elecricity works, they are;\n1.Current which is defined as the rate of flow of charge,i.e. how fast charges movein a medium, you see electrons are (negatively) charged particles, when a couple of electons move(say in a wire) current is said to flow, based on how well electrons will flow in a material all materials are classified under cconductors(like metals) and insulators(like wood).Conductors have higer 'conductivities'than wood. this is important to note because based on the molecular structures of materials electrons dont always flow as freely as they would like, the atoms in the material(based on the ambient temperature) offer opposition to the flow of electrons, this is called resistance.For short you could say current is the flow of electrons.\n2.Voltage, which is what causes the electons to flow, it works by creating differnt levels of voltage at the end of the wire much like having a pipe at different levels of height so water can flow. if the pipe were flat on the floor the water will remain where it is.\n\nThis flow of electons is useful for example in the simple light bulb which works by a material givivg of light and heat as its form of reistance (mentioned earlier)in other words only when current flows in this material, will light come on.\n\nElecricity is the flow of current(or electrons form the explanation above)\n\nEnginners and scientists always find ways of getting the right amount of voltage and current based on their understanding of the behavior of materials to acheive all the electrical feats you've seen.\n\nReminds me of a question i was asked once 'if electricity is just a flow of electrons meaning all the electrons coming into my house leaves eventually, then why do i pay bills'. I am sure you can answer now that the electrons may be free but the voltage for driving it is not free. This is what generating stations generate.
218186
AC (alternating current) can be transformed into a DC (direct current) by means of a rectifier or bridge rectifier circuit depending on the AC circuit.\n\nA single AC line to ground or common an be rectified by the use of a single diode. This is a crude dc circuit.\n\nUsing a dual AC line, not grounded, where there are two lines, both above ground, then a full wave bridge rectifier can be used. Four diodes are used which rectify both the positive half as well as the negative half of the AC waveform.\n\nThen there is the 3phase rectifier bridge which uses 6 diodes, converting 3 AC lines, they are 120^deg outof phase of each other. Most industrial machines are using 3 phase power.\n\nMachines using this 3 phase power usually have a Motor Control Center which house a AC Drive (AC to DC to AC) inverter. This drive uses devices called IGBT which are active diode devices providing controlled amounts of power at variable frequency to run a machine.\n\nTo smooth out the DC waveform a capacitor bank is attached to the output of the DC bridge rectifier. \n\nAs you drive by an industrial park you will notice three power lines usually connected to each building. This is the 3 phase power. \n\nLarge Hybrid electric vehicles use such machines.