Transformers are electronic devices that transfer electrical energy from a electric circuit to another or even across multiple circuits. the passage of a electric current alternating on either of the two coils of a transformer generates a flowmagneticvariable in its metallic core, causing the emergence of a induced electromotive force on the other coil. It is through the Faraday's law of induction, discovered in 1831, which describes the effect of the electrical voltage induced in the transformer coils due to changes in the magnetic field flux.
Furthermore, understand the operation of transformers, which are technological applications directly derived from the study of Faraday's induction, is of great importance for the understanding of important concepts of the electromagnetism.
See too: Ielectromagnetic nduction - the working principle of transformers
What is a transformer and what is it for?
Transformer is a device capable of lowering or lowering voltage and electrical current supplied to any electrical circuit. Operate exclusively with alternating currents and its ability to increase or decrease a Electric tension is directly related to the number of turns in which a conducting wire is wound around two ends of an iron core, called a windingsprimary and secondary.
This iron core is usually built in a rectangular shape or in U shape.Furthermore, it is also common for it to be constituted as a combination of several blades of iron, placed in close contact, in order to avoid larger energy losses.
How does the transformer work?
The operation of transformers is based on a physical phenomenon known as electromagnetic induction, discovered by Michael Faraday and described through the Faraday-Neumann-Lenz law.
The passage of electric current through the main winding of a transformer gives rise to a magnetic field oscillating. This variable magnetic field propagates more easily inside the iron core, so it is conducted towards the secondary winding, thus inducing the formation of a alternating electric current in this winding.
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The relationship between the number of turns of each winding indicates whether there is an increase or decrease in current and voltage intensity. If the number of turns in each winding is equal, both the current and the electrical voltage are equal in intensity in the circuits. primary and secondary, however if the number of turns in the primary winding is greater than in the secondary winding, the voltage electrical current in this second winding will be smaller and the electrical current will consequently increase in the same measure as the voltage that is reduced.
the part of electric power which is not transmitted between the transformer windings usually turns into heat dissipated, due to the andmade joule. For this reason, transformers are often soaked in high fluids. thermal capacity, which hardly heat up and, therefore, regulate the operating temperature of these devices. It is worth mentioning that transformers stand out as large electrical devices. efficiencyenergy, once Yield average of these devices easily reaches 96% to 99%.
The small percentage of energy that dissipates in transformers is mainly due to the hysteresis magnetic resonance of the iron core and the emergence of chainsparasites (or Eddy currents).
See too:What is the difference between conductors and insulators?
Transformers formulas
The main formula used for the transformers is the one that relates to voltageelectric it's the numberinwindings in the primary and secondary circuits. Look:
UP mes – electrical voltage in the primary and secondary windings
NP and nos – number of turns in the primary and secondary windings
In addition to the formula above, there is a formula that relates to chainelectric in the windings with the number of turns:
iP Heys– electrical currents in the primary and secondary windings
Solved exercises on transformers
Question 1 - (Coffee)Tasers are electroshock weapons that use an electric current to immobilize people who are posing a threat to someone or public order. The weapon's internal system creates and treats the electrical current that will be discharged through the copper wires. Capacitors, transformers and batteries are fundamental parts in this process.
Source: Available at: < https://www.tecmundo.com.br/infografico/12216-a-tecnologia-das-armas-taser-infografico-.htm>. Adapted. Accessed on: September 3rd. 2017.
In this sense, check the alternative correct which completes the gaps in the following sentences:
The transformer is an electrical equipment that has its operating principle based on __________. The battery is an energy source that transforms __________ energy into electrical energy. The capacitor is a device that stores __________.
a) Coulomb's law - thermal - magnetic field
b) Lenz's Law - luminous - electric current
c) Faraday's law - chemistry - electrical charges
d) Newton's law - magnetic - electrical resistance
Template: letter C.
Transformers are equipment based on Faraday and Lenz laws. Batteries are devices that transform energy chemistry in electrical energy through spontaneous redox reactions. Capacitor is an electronic device whose basic function is to store electrical charges, consequently it is an accumulator of electrical potential energy.
question 2 -(Uerj) The physical principle of operation of alternators and transformers, demonstrable experimentally, refers to the production of electrical current through the variationof a magnetic field applied to an electrical circuit.
This principle is based on the so-called law of:
a) Newton
b) Ampere
c) Faraday
d) Coulomb
Template: letter C. Faraday's law of induction states that varying the magnetic flux through a conductor, such as a coil, results in the production of an induced electromotive force..
By Rafael Hellerbrock
Physics teacher
Would you like to reference this text in a school or academic work? Look:
HELERBROCK, Rafael. "Transformers"; Brazil School. Available in: https://brasilescola.uol.com.br/fisica/transformadores.htm. Accessed on June 27, 2021.
