Study Material

Dynamic Electricity

What is dynamic electricity?

The dynamic electricity is the orderly movement of electric charges inside a conductor. It manifests as an electrical current, which can be manipulated to carry out a task.

An example of dynamic electricity is that which circulates in electrical circuits

An example of dynamic electricity is that which circulates in electrical circuits

To establish an electric current, a source is necessary that is responsible for keeping the electric charges flowing. This source can be a battery or a generator of some kind.

In addition, the environment in which the charges move must facilitate their movement, therefore conductive materials, such as metals, are especially suitable.

Metals have one or two electrons loosely bound to the nucleus in its outermost shell, making it easy for them to move from one atom to another. Normally these movements are random, that is, in any direction, so the net movement is zero.

However, by establishing a potential difference between the ends of the conductor, thanks to a battery, an electric field is created inside the metal, which drives the free electrons towards the positive pole of the cell.

Obviously, the path of the free electrons within the conductor is not entirely direct, since there are many obstacles, such as the other particles and the existing impurities. This ultimately causes a slow, dragging or drifting movement of the electrons within the conductor.

It should be noted the fact that the electric current is generated by the movement of any charged particle. It is easy to make electrons flow inside a copper wire, but in general, a set of ions, positive or negative, can start up in an orderly fashion and generate an electric current.

Characteristics of dynamic electricity

-Dynamic electricity consists of moving electric charges, and they generate the electric current.

-To keep the loads flowing, an agent is needed to do the work necessary to keep them moving continuously.

-In the International System of Units the charge is measured in coulombs, abbreviated C and the current in coulombs / second, a unit that is called ampere, which is abbreviated A. A current of 1 A means that by the cross-sectional area of the conductor flows 1 C every second.

-The average current in a conductor is calculated through:

m = Δq / Δt

Where Δq is the amount of charge that passes through the cross-sectional area in the time interval Δt.

-The electric current always needs a closed path to maintain its flow. This path is called a circuit and it must be closed, because when the current flowing through it is opened it stops.

-In principle, the direction of the current is the movement followed by the electrons in the conductor, which leave the negative pole of the battery and go to the positive.

However, by convention, the current is always drawn leaving the positive pole, that is, as if the charge carriers were positive in sign. This is why current is always seen coming out of the + pole in circuit diagrams fed by a direct source.

-All moving charge produces a magnetic field, so a current-carrying wire always generates one.

Types of current

Electric current has two variants:

  • Direct current : it is the one that always flows in the same direction, like that provided by common batteries.
  • Alternating current : periodically changes direction and is produced by an alternating current generator. It is also the one obtained at the exit of domestic outlets.

Examples of dynamic electricity

Electrical circuits

Dynamic electricity is present in the current that circulates in any electrical circuit, however simple it may be. It is needed to turn on flashlights, electric stoves, telephones, and all kinds of appliances, and it also powers the car’s electrical system.

Electricity transmission systems

Electricity transmission systems use dynamic electricity in the form of alternating current, because it is easier to conduct over long distances and with lower losses, to get from power plants to houses and streets.

Atmospheric electricity

Electric currents are generated in the Earth ‘s atmosphere , which is synonymous with dynamic electricity.

Specifically in the ionosphere, ultraviolet radiation from the Sun originates charged particles that flow in large circuits of electrical current at high altitude.

Terrestrial electricity

Numerous electrical currents circulate in the earth’s crust, due to chemical reactions that take place in the subsoil.

The Earth has its own magnetic field. Inside, the flow of molten iron in the core of the planet generates electric currents, and these are responsible for creating the Earth’s magnetic field.

Polar auroras

An aurora borealis.
An aurora borealis.

The polar auroras (austral or boreal) are regions of the night sky with bright and beautiful colors, which appear near the poles.

They are due to dynamic electricity, since a stream of charged particles continually arrives from the Sun, which is known as the solar wind . When these particles approach the Earth, the magnetic field of this deflects them, and in doing so, light is emitted, creating the luminous effects of the aurora.

Functioning of the nervous system:

Stimuli from outside reach the senses and the information received travels through the nervous system through electrical impulses to the brain, where they are processed properly. For this, small electrical currents are needed to carry the information.

In the same way, the movement of the muscles depends on electrical impulses that travel from the brain carrying the orders of the movement.

Defibrillators:

Dynamic electricity can severely damage the body, a current of 1 A can be fatal. But used properly, an electrical current helps save lives, as in the case of a defibrillator.

The defibrillator is a device that, through large capacitors, sends an electrical current to the heart, to help it restore its rhythm after a heart attack.

Differences between dynamic electricity and static electricity:

-In static electricity, the electric charge accumulates in certain areas of the material, while the dynamic, being electric current, flows through the conductors.

– Rubbing is the main mechanism for the formation of static electricity, while dynamic electricity requires a source that keeps charges moving. This is achieved through chemical reactions that occur inside a battery, or through alternating current electromechanical generators, based on Faraday’s law of induction.

-Insulating materials are the main support for static electricity, while electric current needs the conductors. This is because, unlike conductors like copper and other metals, insulators lack free electrons. In these, the charge only accumulates, with little possibility of circulating.

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