Voltage is a measurement of electromotive force and the electrical potential difference between two points of a conductor. The volt is the SI derived unit for voltage in the metric system. Volts can be abbreviated as V ; for example, 1 volt can be written as 1 V.
Ohm's Law states the current between two points on a conductor is proportional to the voltage and inversely proportional to the resistance. Using Ohm's Law, it's possible to express the potential difference in volts as an expression using current and resistance. When the Earth interacts with us, it attempts to decrease our gravitational potential, because we have a certain mass.
As part of this interaction, the Earth pulls us downward, and we let it, enjoying our ride down a mountain slope on skis or a snowboard. Similarly, an electric potential field that acts upon charged particles aims to bring the particles with the opposite charge together and to push particles with a similar charge apart.
We can conclude from the above that an electrically charged body tries to reduce its electric potential. To do so it attempts to get as close as possible to the high-capacity source of an electrical field with the opposite charge, as long as other forces are not preventing it from doing so. If the electric charge of the objects is the same, each of the electrically charged objects attempts to decrease its electric potential by moving as far as possible away from the similarly charged source of a powerful electrical field.
Again, this is only the case if no other forces are preventing this from occurring. If there are forces that act to prevent this, the electric potential does not change. In the analogy with gravity, when you are standing at the top of the mountain, the force of gravity is compensated by the reaction force of the ground and nothing pulls you down and off this mountain.
It is only your weight that pushes the skis. However, as soon as you push off… off you go down the hill! Similarly, an electric field created by a charged particle or a group of particles acts upon other charged particles. It creates an electric potential to move these charged particles towards each other or away from each other, depending on whether the charge between these two interacting particles or objects is similar or opposite.
When a charged particle is introduced into an electric field, it has a certain amount of energy that can be used to perform work. Electric potential is a term that describes this energy stored at each point of an electric field. The electric potential of an electric field in a given point equals the work that the forces of this field can perform when a unit of positive charge is moved outside the field. Looking again at the analogy with the gravitational field we can conclude that the notion of electric potential is similar to the phenomenon of the level of different points on the surface of the Earth.
As we discuss below, the work of raising a body above the ground depends on how high we need to lift that body, and similarly, the work of moving one charge away from another depends on how far away those charges are. Let us imagine Sisyphus, one of the heroes of the myths of Ancient Greece.
He was doomed by the gods to do meaningless work in the afterlife, rolling an enormous stone to the top of a mountain as punishment for the sins he committed during his life. To bring the stone halfway up the mountain he would perform half of the work that he needs to perform to bring the stone all the way to the top.
Once he brought the stone all the way, the gods pushed it off the mountain. To reach the bottom the stone itself also performed some work. We usually count the height from sea level, which is considered to be the height of zero. Using this analogy we can say that the electric potential of the surface of the Earth is a null potential, that is.
This value quantifies the ability of an electric field to perform work W to move a charge q from one given point to another point:. The notion of voltage was introduced by Georg Ohm , a German physicist. This law can be written by using this formula:. An alternative definition of electric voltage describes it as a ratio of the work that an electric field performs in order to move an electric charge to the magnitude of this charge.
A voltage of one volt is equivalent to the voltage of an electric field that performs the work of one joule to move a charge of 1 coulomb.
We can define a volt by using other SI units as follows:. Voltage can be generated by different sources such as biological systems and entities, electronic and mechanical devices, and even by various processes in the atmosphere.
An elementary unit for any biological system is a cell, which can be viewed as a small electrochemical generator. Some organs of living organisms such as the heart that are formed by many cells produce a higher voltage. It is interesting to note that different species of sharks, which are the perfect predators of the oceans and seas, have very sensitive sensors for voltage.
These sensors are known as the lateral line , and they allow the sharks to detect their prey by their heartbeat. This mechanism is very reliable. While talking about voltage in the animal world, we should also mention electric rays and eels, who have developed a method to attack their prey and to fight off their predators by generating a voltage over V during the process of evolution. People have been able to generate electricity and create the difference of potentials by rubbing a piece of amber with wool or fur for a long time, but a galvanic cell is considered to be the first device to generate electricity.
It was created by the Italian scientist and physician Luigi Galvani , who discovered that the difference of potentials occurs when different metals and electrolytes come in contact with each other.
Another Italian physicist, Alessandro Volta , continued and further developed this research. Volta was the first person in the world to submerge sheets of zinc and copper into acid, in order to generate direct electric current. Thus, he created the first chemical source of electric current. He connected several of these sources in series to create the first chemical battery. It became known as a voltaic pile and allowed people to generate electricity using chemical reactions.
Thanks to him we now have reliable electrochemical sources of energy. While talking about researchers who worked on creating devices to generate electricity, we should not forget the Dutch physicist Van de Graaff. He created a high voltage generator known now as the Van de Graaff generator. When generating electricity it uses the same principle of the division of charges that we facilitate when rubbing amber with wool or fur.
We can say that two outstanding American scientists Thomas Edison and Nikola Tesla were the fathers of modern electric generators. A patent war followed and humanity benefited from it, thanks to the work of these two scientists.
There are billions of devices made today that use the mechanism employed in these reversible machines. We can find them under the hood of our car, in a power window regulator, or a blender, among other devices. On the other hand, it was Tesla, who discovered ways to generate alternating current and the principle of transforming it.
These discoveries are used by devices such as electric transformers, power lines that transport electricity over long distances, and others. There are multitudes of these devices as well, and they include many consumer electronics frequently used by us in daily life, such as fans, refrigerators, air conditioners, vacuum cleaners, and many other devices that we cannot describe here due to the scope of this article.
Eventually, scientists discovered other electric generators that use different principles, including those that employ the energy of nuclear fission. Some of these other generators are meant to serve as energy sources during long trips to outer space.
If we do not consider some of the generators created for scientific research, we can say that the most powerful sources of electric energy on Earth are still the atmospheric processes. Kv is called as Kilo Volts or Volts. Voltage is electrical pressure and one half of power…. KV — This is a measure of voltage in kilo volts. This is the potential energy that can be given, if it were consumed it would be expressed as Watts W. KW is called as Kilo Watts or Watts. The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power.
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