Alternating current


The alternating current , abbreviated shown as AC , is considered as a flow of charging power is reversed so periodic that one can say that starts from zero and increases to a maximum , decreases to zero, inverted , reaches a maximum in the opposite direction , back again to the original value and repeats this cycle in a manner indefinitely . The time interval between achieving a defined value intwo successive cycles is called the period , the number of cycles or periods per second is the frequency , and the maximum value in any direction is the amplitude of the alternating current.


What is AC?

It is the type of electric current whose main characteristic is magnitude and direction , which have a variation in their cyclical type through a curve that rises and falls through a wave .

  • Characteristics of alternating current
  • Source
  • History
  • Who discovered
  • What is it for
  • How it is produced
  • Frequency
  • Advantage
  • As measured
  • How it differs from direct current
  • How direct current is converted into alternating current
  • Examples of appliances that work with alternating current

Characteristics of alternating current

The main characteristics that we can observe in alternating current are the following:

  • The way that alternating current oscillates is sinusoidal .
  • It has the ability to transmit energy in an efficient way.
  • Its magnitude and direction shows a cyclical variation .
  • Its symbol is represented by the letters CA .
  • It occurs when the flow of the electric current varies from time to time.


Its origin dates back to the year 1882 when the physicist , mathematician , inventor and engineer named Nikola Tesla , designed and built the first induction motor of current AC . Later, the physicist William Stanley , again used the principle of induction to transfer alternating current between two electrically isolated circuits .


When the thrust of the alternating current is created, it entailed winding a pair of coils on a basis of iron which was known as coil induction . This was the way in which the precursor of the current transformer was obtained . The system used today was created by Nikola Tesla ; and the distribution of alternating current was in charge of George Westinghouse . Lucien Gaulard , John Gibbs and Oliver Shallen also contributed to the development and improvement of this system. . The first interurban alternating current transmission occurred in 1891 in Colorado and later it occurred in Germany.

Who discovered

The first alternator to produce alternating current was made by means of a dynamoelectric generator based on the principles of Michael Faraday , and which was built by the French instrument maker Hippolyte Pixii in 1832.

What is it for

Alternating current is the way many appliances work properly when plugged into a wall socket . It also serves to provide electricity to homes, it is also used in the telephone , radio , television . Probably one of the most important uses of alternating current is the supply of motive power for electric motors used in pumps , compressors , machines , tools .

How it is produced

It is produced in alternating current generators . This process occurs when a coil moves in front of a magnet causing electrons to move in the coil wire. Depending on the amount of electrons that oscillate in each section of a conductor will be the intensity of the alternating current.


The frequency of the alternating current is a physical phenomenon that is repeated in a cyclical in a certain number of times over a B time. In order to determine the frequency of the alternating current, the following formula must be applied :

F = P x Vg / 120


  • F : is the frequency in Hz
  • P : is the number of poles which must always be even
  • Vg : is the turning speed .


The advantages of alternating current are:

  • It offers the possibility of producing cheaper and more efficient generators and motors , while at the same time being less complex .
  • They have the possibility of transforming the voltage in a very simple and cheap way by means of transformers .
  • Possibility of transporting large amounts of power over long distances using thus the minimum of stress .
  • Possibility of manufacturing very simple motors .
  • Disappearance of some electrical phenomena that are not desirable, such as magnetization in machines, and polarizations and electrolytic corrosion in metallic pairs.

As measured

For sinusoidal signals of alternating current the following equation is used:

instantaneous = V p sin Ө


  • V is the instantaneous value of the voltage , that is, the value at a given instant t.
  • Vp is the peak value of the voltage , which is also known as the amplitude of the voltage.
  • k is a constant of the current in question and is related to frequency .
  • t is the time expressed in seconds

How it differs from direct current

Alternating current is a type of electrical current where the direction of the flow of electrons comes and goes either through regular intervals or in cycles . This is the type of current that normally travels through power lines and is the electricity that we find in homes in wall sockets . Current DC is the electric current flowing to constantly in the same direction as the flowing apparatuses using batteries .

How direct current is converted into alternating current

In order to transform a direct current into an alternating current we have to turn on and off so continuous and repeated and high speed the power supply via a switch . Devices that have the ability to do this are called Chopper . Adding a coil induces a current in the opposite direction to the original when the switch is turned on.

Examples of appliances that work with alternating current

Some examples of devices that work with this type of current are:

  • Washing machine
  • Drying machine
  • Refrigerator
  • Kiln
  • TV
  • Music equipment
  • Computer

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