Electric current: what is it, how does it work, types, effects – Ferrovial

An electric current is the physical phenomenon of the displacement or flow of an electric charge, usually of electrons, by means of a conductive material. In order for there to be an electric current, the electrons furthest from the nucleus of an atom of a certain material must detach and circulate freely through a conductor in an electrical circuit. 

The intensity of the electric current is determined by the amount of charge passing through a conductor in a unit of time. The intensity is measured in coulombs per second (C/s), which is equivalent to one ampere (A), and the measuring instruments par excellence for electric current are the galvanometer and the ammeter.

How does electric current work?

An electric current is the movement of particles, starting at the moment when an external voltage is applied at one of the ends of the conductor. That, in turn, generates an electric field on the negatively charged electrons that are attracted to the positive terminal of the external voltage.

For the electric current to be transmitted from one point to another, there must be materials with a high amount of free electrons located in the last orbit of their nucleus, which means they are highly susceptible to moving due to the weaker attractive force on them from their nucleus.

What is the formula for electric current?

Ohm’s Law determines the formula for electric current:

Current = Voltage / Resistance.

• Resistance represents the obstacle that electrons face in their path. Its unit of measurement is the ohm.
• Current is a quality of the electric current. Its unit of measurement is the ampere.
• Voltage represents the power difference between one point and another. Its unit of measurement is the volt.

What types of electric current are there?

Electric current can be classified according to its nature:

1. Direct current (DC): consists of the displacement of electrical charges that do not change their direction of travel over time.
2. Alternating current (AC): the current’s direction and plane of movement vary cyclically, the opposite of direct current. This is an efficient current, so it is commonly used in homes and businesses.
3. Three-phase current: consists of three alternating currents with the same frequency and amplitude called phases. 
4. Single-phase current: this type of current is obtained from a single phase of the three-phase current and a neutral cable that makes it possible to use low-voltage energy.

 What kinds of materials are there for electrical conduction?

1. Conductive materials: these offer little resistance to the flow of electricity. Electrons move about freely because they are attached to atoms in a very weak way, so they can conduct a lot of electricity.
2. Semiconductor materials: these can act as conductors or insulators, depending on the electric field where they’re implemented.
3. Insulating materials: electrons do not circulate freely, so they are not considered conductors of electric current.

What are the effects of electric current?

An electric current can have various effects. Some of these include:

• Heat: a product of the conductor’s temperature increase due to the flow of the electric current. One example of this is a stove.
• Magnetic: when an electric current passes through a conductor, it creates a magnetic field around it. This effect can be seen with televisions, radios, ammeters, etc.
• Physiological: there are electro-medical devices that respond to the effect of electrical conduction, generating electrical shocks where applied.
• Chemical: the effect generated by the flow of an electric current through an electrolyte, which batteries are based on.