Little by little we are entering more and more into the world of electricity. In this issue we begin to look in detail at the elements that make up an electrical circuit, so we will know what they are made of and how electrical appliances work, I have considered it necessary to begin by describing the element that will be present in all circuits that we can find and without which these would not be possible, I mean the electrical conductor, of course, I will immediately define what is an electrical circuit taking into account that I want to make these publications in such a way that it is easy for everyone to understand.
Which are collections of circuit elements connected together, are the most fundamental structures of electrical engineering. A circuit is an interconnection of simple electrical devices that have at least one closed path in which current may flow. However, we may have to clarify to some of our readers what is meant by “current” and “electrical device,” a task that we shall undertake shortly. Circuits are important in electrical engineering because they process electrical signals, which carry energy and information; a signal can be any timevarying electrical quantity.1
The electrical circuits are the ones that allow us to analyze the behavior of electricity based on the elements that make it up, so we control that our electrical devices do not receive more energy than necessary but the appropriate one, also according to the components that make up the circuit can be obtained a large number of applications, from electrical protections to the latest generation computers, once you know the elements and the necessary mathematics the limit will be set by your imagination.
The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor. The inverse quantity is electrical conductance, and is the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with the notion of mechanical friction. The SI unit of electrical resistance is the ohm (Ω), while electrical conductance is measured in siemens (S). 2
Resistance is opposition, electrical resistance is opposed to the passage of current, that is why it is used to limit the amount of energy received by the elements of a circuit, but its function is not only to protect, these resistors convert electrical energy into thermal energy, in many cases this could be considered as a loss of energy because heat is dissipated in the environment, but this property has been used to create plates, cookers, water heaters, defrost in refrigerators and many other applications in which heat needs to be generated. Electrical resistance is a variable that can be measured in all natural elements, hence we can classify these elements as conductors and insulators (in electrical terms).
In a simple definition we could say that an electrical conductor is a body whose material has little resistance to the passage of electric current, are used to interconnect circuits and transport electrical energy over long distances, an insulator is a body whose physical properties prevent the passage of current through it, are used for protections in electrical networks. There are man-made conductors and insulators, but naturally materials have a resistivity coefficient ρ which can determine which materials are good conductors of electricity and which are insulators, the resistance of the body depends on this coefficient, the volume and length of the body and the temperature at which it is at the time of being energized.
R=ρ x l/S
Where ρ is the proportionality coefficient or the resistivity of the material, l is the length of the cable and S the area of the cross-section of the cable.
We can use the following table to find the Properties of Metals and Alloys
In the next installment I will be sharing about resistances in the electrical circuits, behavior, disposition and Ohm's Law. I hope I have been able to contribute with your knowledge, we read in the next issue.
CAUTION: Never do anything with electricity that you're not sure of, it's easier and less trouble to ask someone who understands.
Sources
1Mulukutla S. Sarma. Introduction to Electrical Engineering, (page 3),
New York Oxford
OXFORD UNIVERSITY PRESS
2001
3C. JAMES ERICKSON Retired Principal Consultant, E. I. du Pont de Nemours & Co., Inc.
CHARLES D. POTTS Retired Project Engineer, E. I. du Pont de Nemours & Co., Inc.
BYRON M. JONES Consulting Engineer, Assistant Professor of Electrical Engineering,
University of Wisconsin—Platteville. Electrical and Electronics Engineering
