THE movementof theloadselectric is the phenomenon behind the functioning of electronic devices. when a electric charge, of cargo positive or negative, moves due to the influence of an external electric field, we say that an electric current is formed.
Lookalso: What is an electric field?
What is electric current?
THE electric current is one of the fundamental quantities of physics, and its unit, according to the International System, is the Ampere (THE). an electric current of 1 Ampere implies that for 1 second, passed 1 Coulomb of electrical charges through a cross section made somewhere in space. Look at the figure below:
Cross section of a conducting wire being crossed by several electrons.
As long as there are any number of electrical charges crossing the cross section shown above there will be electrical current in the material.
The definition of electrical current is quite simple. Watch:
electric current is the flow chaotic of charge-carrying particles across the cross-section of a given position in space and through the application of an electric field. |
The electric current can be calculated as the ratio of the load modulus that crosses that section every second:
i - electric current
ΔQ – amount of electrical charge
t - time interval
What is the difference between electric charge and electric current?
Chainelectric it is the movement of electrical charges in some preferential direction of the conductor. Electric charge, in turn, is an intrinsic property of matter. Much of the existing particles, such as protons and the electrons, has an electrical charge and, therefore, it can be attracted or repelled by other electrical charges.
The amount of electrical charges present in a body can be calculated using the following formula:
Q – electrical load module
no – number of cargo carriers
and – fundamental load (1.6.10-19 Ç)
protons and electrons they are the most common charge carriers, despite being particles of different masses and electrical charges of opposite sign. The amount of charge present in these particles is equal and is called chargefundamental, whose modulus is approximately 1.6.10-19 Ç.
Movement of electrical particles within wires
When we connect two points of a threadconductor to one potential difference, connecting it to a battery (generator) or a socket, for example, an electric field is formed inside of the wires, responsible for the emergence of an electrical force that drags the electrons towards the terminal positive or negative.
O fieldelectric it is formed in the conductor at the speed of light, that is, the “order” of movement of the electrons is practically immediate, so that all these particles feel the action of the electrical force dragging them. However, the movement of these charges is quiteslow, due to the various mutual interactions between electrons and also the frequent collisions between the electrons and the atoms that form the crystal lattice of metals, which causes a great loss of velocity. This speed at which electrons are conducted in a material, that is, the speed of chainelectric, is called velocityindrag, and its modulus is on the order of centimeters per minute.
Schematic showing the electrical current inside a conductor wire
Joule Effect
When electrons collide with the atoms of the material in which they move, they transfer part of their kinetic energy, promoting the vibration of the crystalline network of this medium. This vibration causes an increase in the temperature of the material, configuring the so-called Joule effect.
The Joule effect is the basis of the functioning of the incandescent lamp: the transfer of energy from the electrons to the atoms causes a great heating of the wire.
Electrical charges on conductors, insulators and semiconductors
→ Conductors
All conductive materials, like most metals, have a large number of carriersinchargefree, that is, loosely bound to the material's atomic nuclei. These charge carriers are electrons, very light particles and electric chargenegative.
At room temperature (25°C), for example, electronsfreeFromconductors they are not standing still, but neither are they being led between one point of the material and another. In this case, the agitationthermal of the material is transmitted to the electrons, causing these particles to move chaotically, in different speeds and directions, so that the total displacement of the electrons is approximately null. When this occurs, we say that the driver is in electrostatic balance.
→ Insulators
Materials equipped with greatresistanceelectric, calls of insulators, naturally have few or no electrical charge carriers that are free and that can be dragged by the action of the electric field. In these materials, it is necessary to apply large electric fields until their ionization occurs. This process explains the formation of rays and is called breakgivesrigiditydielectric. In the case of lightning, atmospheric air, which is an insulating medium, supports the movement of cargo by the formation of a large electric field with the electrified clouds or between the clouds and the soil.
Read too: Five fun facts about the rays that will make your hair stand on end
Large electric fields can ionize air, promoting electron conduction.
→ Semiconductors
In materialssemiconductors, in turn, the charge carriers are partially linked with their atomic nuclei due to a weak electrical interaction. It is possible to make them free charge carriers by providing some form of energy to these particles: heating the material (thermoelectric materials), mechanical interaction (piezoelectric materials), lighting (photoelectric materials) etc.
At the vacuum or in materials that do not have any electrical resistance, electrical charge carriers can move without any difficulties. In these ways, by sensing the action of an electric field, charge carriers can move at great speeds in the direction of the strengthelectric that acts on them.
Movement of cargoes in liquids
When we put some solution linked to a potential difference, an electric field is formed in this liquid, and the ions dissolved in this solution themselves move to the poles that have a charge opposite to their own. In this case, we say that a chainionic is formed.
direction of electric current
When we study the movement of electrical charges in electrical circuits, it is common to hear that electrical current can have two directions: the direction real and the sense conventional. This convention came about because charge carriers in conductors have chargenegative. Understand: in the real sense, when we connect a wire to a potential difference, the electrons move towards the pole positive. This direction of current is called sensereal.
O senseconventional of the current, in turn, admits that the charge carriers of the conductors have positive electric charge, so that when we connect a wire to a potential difference, these electrons move towards the potential. negative.
Lookalso: direction of electric current
By Me. Rafael Helerbrock
Source: Brazil School - https://brasilescola.uol.com.br/fisica/cargas-eletricas-movimento.htm
