Alternating current and direct current

Alternating current is the flow of electrical charge that varies in direction, with changes in voltage and current.

Direct current is an electrical flow that remains constant and there are no changes in voltage.

The difference between alternating current and direct current not only has to do with the characteristics of the electrical flow, but with the applications of each one in everyday life..

	Alternating current	Direct current
Definition	It is a type of current with variable electrical flow.	It is a type of current whose electrical flow remains constant.
Source	1832, by Hippolye Pixii.	1800, by Nicola Volta.
Advantage	Greater efficiency of use. Energy transport is cheaper. Use for domestic and industrial purposes. Can be converted to direct current.	It is stored in the form of batteries. Is safer. Allows use on multiple devices without depending on a connection.
Applications	Street lighting.	Car batteries.

What is AC?

Alternating current is a type of current in which the electrical flow varies in magnitude (voltage value) and direction (voltage direction), alternating in certain periods of time.

These variations generate different forms in the oscillation, the most common being the sinusoidal oscillation, with which a much more efficient energy transmission is obtained and, therefore, is one of the most used..

Other forms of oscillation of alternating current, such as triangular or rectangular, have very specific applications, such as electronics and mathematical studies..

Origin of alternating current

In 1832, the Parisian inventor Hippolyte Pixii created an alternating current generator, based on the principles of the magnetic field of the British physicist and chemist Michael Faraday. This allowed experimenting and developing different applications, especially in Europe..

However, it was the physicist and inventor Nicola Tesla who, in 1882, built the first alternating current induction motor. This allowed the transformation of alternating current into direct current, using a motor as a kind of converter..

Subsequently, and seeing the scope that alternating current could have in everyday life, he developed a transformer that allowed the electrical voltage to rise and decrease its intensity to be able to transmit the current over long distances, and then reduce the voltage when reaching the point consumption so that it could be used efficiently.

The importance of the invention of the transformer lies, fundamentally, in an issue of efficiency and safety, since it represented a dangerous situation that a common home received a high amount of electrical energy.

In addition, direct current cannot travel over long distances without generating significant energy losses, something that alternating current can do..

Therefore, with these developments the doors were opened to improve the quality of life and accelerate industrialization processes, especially in urban environments, since although electricity already existed and was applied for practical purposes, it was done with direct current. , which due to its characteristics turned out to be impractical compared to alternating current.

Finally, in 1891, it was possible to verify the efficiency not only of the alternating current, but of the generator and transformer created by Tesla, when the first interurban current transmission was made in Colorado, United States.

Components of alternating current

• Cycle: is the variation in electrical voltage from zero to a positive maximum value, then to zero and from there to a negative maximum value.
• Period: the time in which a cycle occurs. It is expressed in seconds.
• Frequency: the number of cycles per unit of time (seconds). It is expressed in Hertz (Hz). In the American continent, the standard frequency is 60 Hz and in Europe and the rest of the world, 50 Hz.

Advantages of alternating current

• More efficient generators with respect to direct current.
• Possibility of generating voltage and current changes safely and economically with transformers.
• Power transmission over longer distances and at high voltage using fewer electrical conductors.
• Allows a greater range of voltages with the use of the transformer.
• Can be converted to direct current with the use of a rectifier.
• Disappearance or reduction of risks and phenomena associated with the use of electrical energy, as well as electrolytic corrosion and magnetization of metal parts.

Alternating current applications

• Street lighting.
• Domestic and public electrical connections.
• Devices for domestic and industrial use with power connection (household appliances, car wash machines, for example).

What is direct current?

Direct current, also known as direct current, is a flow of electric charge that does not change its direction, so it always goes from the positive pole to the negative pole..

Although direct current was considered not as efficient as alternating current, the reality is that nowadays this type of current has practical applications, especially in the world of electronics..

In addition, the development of high-voltage direct current has replaced alternating current in large systems, such as long-distance submarine cables..

Origin of direct current

Direct current was discovered in 1800 by the Italian physicist Nicola Volta, who developed the first voltaic pile.

After the French inventor Hippolyte Pixii developed his alternating current generator in 1832, and later created a commutator that served as a switch, direct current was obtained. With these technological advances began the generation of electricity in power plants and later, the domestic use of incandescent bulbs based on direct current, by Thomas Edison.

However, after managing the voltages of alternating current with the use of transformers, direct current became impractical..

It was in 1950 that direct current was again considered useful with the transmission of high voltage direct current, which allowed it to be an alternative for systems that required alternating current.

Today, rectifiers are used to change the direct current voltage of devices that require it, such as electronic devices..

Advantages of direct current

• It can be stored in the form of batteries, which makes it possible to have a source of energy available for the devices, appliances, or machines that allow this type of resources..
• In some cases, the batteries can be rechargeable.
• Its use is safer than that of alternating current, which has allowed the development of multiple solutions, especially for domestic purposes..
• Allows use of lower voltages to transmit electricity over cables.

Direct current applications

• Automobiles.
• Underground transportation systems and railways.
• Mobile telephony.
• Computers (they must be powered by alternating current, but internally this is transformed into direct current).
• Any device or appliance that requires the use of batteries.

See also

• Battery and battery
• Conductors, insulators and semiconductors
• Difference between digital system and analog system.