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Topic: Alternating current


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In the News (Thu 18 Apr 19)

  
  Alternating current - Wikipedia, the free encyclopedia
And through the use of alternating current, Charles Proteus Steinmetz of General Electric was able to solve many of the problems associated with electricity generation and transmission.
With alternating current of any frequency, the current is forced towards the outer surface of the wire, and away from the center.
The current flowing on the inner conductor is equal and opposite to the current flowing on the inner surface of the outer tube.
en.wikipedia.org /wiki/Alternating_current   (2633 words)

  
 Direct current - Wikipedia, the free encyclopedia
Direct current installations usually have different types of sockets, switches, and fixtures, mostly due to the low voltages used, from those suitable for alternating current.
It is usually important with a direct current appliance not to reverse polarity unless the device has a diode bridge to correct for this.
High voltage direct current is used for long-distance point-to-point power transmission and for submarine cables, with voltages from a few kilovolts to approximately one megavolt.
en.wikipedia.org /wiki/Direct_current   (480 words)

  
 ALTERNATING CURRENT
The time required for the current to rise to its maximum value is determined by the ratio of inductance, in henrys, to resistance, in ohms.
Current is delayed depending on the mount of inductance.
The phase relationship between current and voltage are opposite to the phase relationship of an inductive circuit.
www.geocities.com /vijayakumar777/electricity/electricity.html   (3112 words)

  
 Glossary: Alternating current / Direct current
Alternating Current (AC) is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles.
Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current.
One advantage of alternating current is that it is relatively cheap to change the tension of the current.
www.greenfacts.org /glossary/abc/alternating-current.htm   (204 words)

  
 War of Currents - Wikipedia, the free encyclopedia
The direct current electric power transmission system had severe limitations that were solved by the use of alternating current.
When Tesla introduced a system for alternating current generators, transformers, motors, wires, and lights in November and December of 1887, it became clear that AC was the future of electric power distribution.
Transmission of electric power by direct current became commercially significant again in the context of high voltage direct current systems, used for bulk transmission of energy from distant generating stations or for interconnection of separate alternating-current systems.
en.wikipedia.org /wiki/War_of_Currents   (1598 words)

  
 Alternating-current electric power - Hutchinson encyclopedia article about Alternating-current electric power   (Site not responding. Last check: 2007-10-22)
Electric current that flows for an interval of time in one direction and then in the opposite direction; that is, a current that flows in alternately reversed directions through or around a circuit.
Electric energy is usually generated as alternating current in a power station, and alternating currents may be used for both power and lighting.
The advantage of alternating current over direct current (DC), as from a battery, is that its voltage can be raised or lowered economically by a transformer;; high voltage for generation and transmission, and low voltage for safe utilization.
encyclopedia.farlex.com /Alternating-current+electric+power   (220 words)

  
 PAControl.com - Three-Phase Alternating Current Motors
Alternating current motors are built in different sizes, shapes, and ratings for many different applications.
The current in phase C has reversed its flow from minus 5 amperes to plus 5 amperes, and the current in phase A has increased from minus 5 amperes to minus 10 amperes.
At instant 6, the current in phase C is minus 10 amperes, and the field extends vertically downward.
www.pacontrol.com /3phasemotors1.html   (2896 words)

  
 alternating current (AC), direct current (DC)
AC current is a specific type of electric current in which the direction of the current's flow is reversed, or alternated, on a regular basis.
Alternating current was chosen early in the 20th century as the North American standard because it presented fewer risks and promised higher reliability than competing DC systems of the day.
Alternating current is still used to deliver electricity to the device, and a transformer is included with these devices to convert AC power to DC power (usually at much lower than the supplied voltage) so that electronic devices can use it.
www.energyvortex.com /energydictionary/alternating_current_(ac)__direct_current_(dc).html   (466 words)

  
 NDT Encyclopedia - MPI: Alternating Current (AC)
Alternating current is current that reverses its direction of flow at regular intervals.
This rectified alternating current for which the rectifier is so connected that the reverse half of the cycle is “turned around”, and fed into the circuit flowing in the same direction as the first half of the cycle.
When a single-phase alternating current is rectified in the simplest manner, the reverse half of the cycle is blocked out entirely.
www.ndt.net /article/az/mpi/alternating_current.htm   (525 words)

  
 Capacitors and Alternating Current   (Site not responding. Last check: 2007-10-22)
You realize that the current and voltage are both going through their individual cycles at the same time during the period the ac voltage is impressed.
The current swing from the positive peak at zero degrees to the negative peak at 180 degrees is NOT a measure of the number of electrons, or the charge on the plates.
I is the symbol for current, and in the word ICE it leads, or comes before, the symbol for voltage, E. C, of course, stands for capacitor.
www.tpub.com /neets/book2/4b.htm   (1147 words)

  
 Compass and alternating current   (Site not responding. Last check: 2007-10-22)
This cycle of the current going positive and negative and the compass swinging back and forth will continue as long as there is alternating current in the conductor.
The compass (a simple meter) will indicate the average value of the alternating current (remember the average value of a sine wave is zero) by vibrating around the zero point on the meter (magnetic north).
When the compass is placed close to the wire and the frequency of the alternating current is high enough, the compass will vibrate around a point that represents the average value of the pulsating direct current, as shown in figure 1-13.
www.tpub.com /neets/book3/7c.htm   (483 words)

  
 Swain Meters - Measuring Unwanted Alternating Current in Pipe
Alternating Current (AC) flowing in a pipe can be a portent of trouble, such as corrosion or harm to persons.
Thus the output vo is a measure of pipe current ii.
The clamp-on AC ammeter is a tool suited to measure alternating current, and to record the magnitude over a time long enough to include representative fault transients.
www.swainmeter.com /unwanted.html   (3018 words)

  
 Production of alternating current
The frequency of an alternating emf (and current) is the number of complete cycles an emf goes through each second.
current because it is the square root of the mean of the square of the current.
Alternating current flows in capacitive circuit, where direct current would not flow.
www.phys.unsw.edu.au /PHYS1111/acc/acc.html   (344 words)

  
 PBS: Tesla - Master of Lightning: Understanding Electricity - AC and DC
With an alternating current the magnetic state of affairs is never a settled one.
Alternating currents do, in a sense, copy their changes of energy into nearby circuits, making energy available there.
For example, power present in the primary as a large current at a low voltage may be transformed into low current at high voltage in the secondary.
www.pbs.org /tesla/ins/ins_acdc.html   (651 words)

  
 Define current - a definition from Whatis.com
Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms.
The common symbol for current is the uppercase letter I. The standard unit is the ampere, symbolized by A. One ampere of current represents one coulomb of electrical charge (6.24 x 10
Direct current (DC) flows in the same direction at all points in time, although the instantaneous magnitude of the current might vary.
whatis.techtarget.com /definition/0,,sid9_gci211871,00.html   (406 words)

  
 LOCATION: LIGHTING and ELECTRICAL - HEALTH - Environmental -- Sensitivities and ALLERGIES; CHRONIC Illnesses.
Incandescent alternating current lighting flickers at the rate of 60 flickers per second.
ALTERNATING CURRENT DEVICES --- refrigerators, blenders, ovens, ranges, toasters, mixers, fans, radios, and televisions may each contribute to the reactive symptoms of AC sensitivity.
Direct current is efficiently transported over short distances and adequate power can be provided at markedly lower voltages than when alternating current is used.
www.earthtym.net /loc-08.htm   (1672 words)

  
 Current Transformers Toroidal Split Core Transformers
Since it is used to measure current, a current transformer is often classified as a type of instrument transformer.
A current transformer can accurately measure the alternating current and put out a reasonable voltage, which is proportional to the current, but without as much heat and size that an appropriate resistor would require.
In application, the toroidal current transformer is slipped over an end of a high current wire or buss bar, which conducts the primary current.
www.butlerwinding.com /elelectronic-transformer/current   (1605 words)

  
 Alternating Current   (Site not responding. Last check: 2007-10-22)
The electrical current in your house is alternating current.
AC, or alternating current means the electrical current is alternating directions in a repetitive pattern.
The frequency of repetition of this current is 60 Hertz.
www.ndt-ed.org /educationresources/HighSchool/Electricity/alternatingcurrent.htm   (275 words)

  
 Alternating current   (Site not responding. Last check: 2007-10-22)
the component is therefore (+A) − of voltage Alternating currents are accompanied by alternating voltages.
Alternating Current simply means that the voltage oscillates
www.pearcable.com From is current by increasing the voltage.
electronics.boekebeurs.be /Alternatingcurrent   (267 words)

  
 Alternating current physics toolbox   (Site not responding. Last check: 2007-10-22)
The root-mean-square (RMS) value of an alternating current is the steady direct current which converts electrical energy to other forms of energy in a given resistance at the same rate as the alternating current (AC).
In layman's terms, although the PD and current have the same period, they do not reach their maximum or minimum at the same time and are out of `sync'.
Either the current or the PD can be ahead and lead or behind and follow, it all depends on the device's and the circuit's configuration.
www.jcphysics.com /toolbox_indiv.php?sub_id=17   (634 words)

  
 IEEE History Center - Alternating Current Electrification, 1886
He thus demonstrated the first practical system for providing electrical illumination using alternating current with transformers to adjust voltage levels of the distribution system.
On March 20,1886, William Stanley demonstrated the first practical system for providing electric illumination with the use of alternating current, and transformers to adjust the voltage levels of the distribution system.
The alternating current system (using transformers) eventually replaced Thomas Edison's direct current system because of the ability to efficiently adjust voltage levels in different parts of the system so as to minimize the inherent power losses associated with distribution.
www.ieee.org /organizations/history_center/stanley.html   (669 words)

  
 Direct and Alternating Current
In the circuit, the current flows at a specific, constant voltage (this is oversimplified somewhat but good enough for our needs.) When you use a flashlight, pocket radio, portable CD player or virtually any other type of portable or battery-powered device, you are using direct current.
While simple direct current circuits are generally described only by their voltage, alternating current circuits require more detail.
In simple terms, the RMS value of an electrical current is the number which represents the same energy that a DC current at that voltage would produce; it is in essence an average of the alternating current waveform.
www.pcguide.com /ref/power/ext/basicsACDC-c.html   (948 words)

  
 Phenomena Cross Reference - ALTERNATING CURRENT   (Site not responding. Last check: 2007-10-22)
Current is the flow of electrical charges (usually electrons) in an electrical circuit.
When you hook a lightbulb to a flashlight battery, the current flows from the negative terminal to the positive terminal, always in the same direction.
The power company uses alternating current because it can be transformed to higher and lower voltages (with transformers) allowing them to transmit and distribute power with lower losses.
www.exploratorium.edu /xref/phenomena/alternating_current.html   (120 words)

  
 What is Alternating Current?
In such cases, we often need to convert alternating current such as the power provided at your wall socket to direct current for use by the load.
At the same time, however, if we were to reduce the system voltage, we would have to increase the amount of current drawn by each car or bus in order to provide the same amount of power to it.
Thus, we use a capital I to represent DC current and a capital V to represent DC voltage.
www.play-hookey.com /ac_theory   (2158 words)

  
 A Dictionary of Physics: alternating current @ HighBeam Research   (Site not responding. Last check: 2007-10-22)
alternating current (a.c.) An electric current that reverses its direction with a constant frequency (f).
If a graph of the current against time has the form of a sine wave, the current is said to be sinusoidal.
Alternating current, unlike direct current, is therefore continuously varying and its magnitude is either given as its peak value (I
highbeam.com /doc/1O83:alternatingcurrent/alternating+current+.html?...   (168 words)

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