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How to understand Electrical Engineering?

By on January 13, 2020

If you are looking to understand Electricity, the first question that comes to anyone’s mind is where and how to begin with. The first step shall be to learn and understand the initial discoveries that laid electricity’s foundation.

Historical facts of the origin of Electrical Engineering

In the year 1881, four units of measurements of Electricity, namely ‘Columb’ ‘Volt,’ ‘Ampere,’ and ‘Ohm’ were announced to measure Voltage (or Electromotive force or potential difference), Current, Resistance, and Charge to recognize the work of  Charles-Augustin de Coulomb 1736-1806,  André-Marie Ampère (1775–1836),  Alessandro Volta  1745-1827 and  George Simon Ohm (1789-1854). These were the four discoveries and measurement units from where the future of electrical engineering began and which make our life comfortable today. Today, it may look like a simple discovery, but it is difficult to believe how much intelligent and painstaking work has gone back to discover such simple rules. It is also to understand the interdependence of the work of each of them. Columb discovered the ‘charge’ behavior, whereas Ampere discovered the behavior of electric current and its magnetic effect. With Volt’s discovery of the battery, it became possible for Ohm to experiment with ease with the amount of current flow and its dependence on resistance. Undoubtedly, these great scientists’ work laid the foundation for all the future fields of electrical engineering.

Basics of Electrical Engineering

The subject of electrical engineering becomes very simple when the fundamentals are understood. ‘Electron’ is the building block for all facets of Electricity. When it is static, it results in the field of ‘Electro-Static,’ and when moving, it results in ‘Electro-dynamic.’

Does electricity originate from the work of Columb?

The static charge was studied in the 17th century by many scientists. Later, Franklin proved that charge flows with its popular kite experiment during stormy and lightning time. It was the work of Columb to understand the behavior of static charges and the formulation of Coulomb’s law, which states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. Coulombic force is one of the principal forces involved in microscopic atomic structure and reactions. The unit coulomb was named after him and is defined as the quantity of electricity transported in one second by a current of one ampere. He also estimated that it is approximately equivalent to 6.24 × 1018 electrons. 

The study of Electro-static, as well as Electrodynamic, is part of Electrical Engineering having applications all around. Since the flow of an electron is not visible and what and how it is doing its function, fundamental engineering must master understanding its behavior under the influence of various factors to visualize the effect and correctly interpret using measuring instruments. In a word, Electrical Engineering is a flow of electrons controlled to derive the advantage the engineer/scientist/innovator wants. The various controlling techniques, such as motion, temperature, static field, etc., give birth to electrical, electronic, instrumentation, etc. engineering. Now, look at the fundamentals of the behavior of electron flow and controlling techniques undergoing development every day.

What is the flow of the electron?

There are electrons in the outermost orbit of the nucleus of every material. These electrons are either bounded firmly or loosely with their nucleus. Where it is bonded loose, it produces a free electron which is always in random motion with high velocity and continuously colliding with each other resulting in zero average velocity. But when such free electrons are subjected to an electric field, it starts drifting; it attains an average velocity, which is very small in the range of less than a centimeter per minute (much smaller than the slowest creature on earth, “Banana Slug”).

What is the drift velocity of the electron/charge?

This average velocity attained by an electron under the influence of the electric field is called drift velocityEvery electron possesses a charge equal to e=1.6×10-19 coulombs, and the number of free electrons in Copper is n=1029 per m3. Therefore, the total charge in Copper shall be Q=1.6×1010 coulombs/m3. The rate of flow of charge is called current. Under the application of an external electric field (also called Voltage), the electric charge starts drifting at drift velocity, which is directly related to the applied electric field.

Drift Velocity versus velocity of propagation of the electric field

The immediate question that will jump into anyone’s mind is ‘when the electron flow is at such a very low average velocity, then how does the lamp glow immediately when the switch is ON“. If it is calculated based on the drift velocity, it will take a few hours. The reason is that the speed of propagation of the electric field from one end to another is at the velocity of light, i.e., 3×108 m/sec, and the electric field drifts the charge at each location of the copper conductor. The charge close to the lamp filament starts doing its job immediately.

Relation between drift velocity, current, and mobility of electron

 The flow of electrons (charge) is also called current (the analogy of water flowing is also called water current). A simple formula determines this current (where n=1029 per m3, e=1.6×10-19 coulombs which are constant).

Hence the current depends on the area of cross-section and drift velocity. The drift velocity depends on the mobility of the electron and the applied electric field. Mobility depends on the property of a material and, in turn, defines the ‘conductivity’ or ‘inverse of resistance.

And therefore, the flow of electrons depends on the property of the material and the applied electric field (Voltage). The International System of Units (SI) of current is Ampere (A) and named after André-Marie Ampère(1775–1836), a French mathematician and physicist considered the father of electrodynamics and in recognition of his work to derive ‘Ampere’s Law.’ He studied the behavior of the flow of charge through a conductor and its magnetic property.  

Analogy

Water flow is the best analogy for understanding the flow of electrons. The water flows under the water head (gravitation head or produced by a water pump). Similarly, the electron flows under the influence of an Electric Field or Voltage/Electro-motive Force and is equivalent to a water head.

What is Voltage or Electro-motive Force?

When an external source is used for the electron (charge) to accumulate at one end of the conductor, the charge difference is called potential difference (also called Voltage or Electro-motive force). A source of energy, such as hydro, coal(steam), heat, solar radiation, wind, geothermal, etc., moves electrons in the conductor. 

Why is electricity the most important source of Energy?

The most important feature of Electricity is its ability to produce using the available energy sources and then transmit and utilize it at the consumer end. With alternating currents, the transmission of electricity to vast distances became feasible. Thus, electrical energy has taken a dominant role compared to any other form of energy in our daily life.

What is voltage?

The unit of Voltage or Emf or potential difference is volt (symbol: V) and is named after the Italian physicist Alessandro Volta (1745–1827). The work of Volta was developing an electric battery and initially termed the accumulation of charge as electromotive force (later called volt in honor of Alessandro Volta). The invention of the electric battery simplified the laboratory setup for further work in the electric current field.

It is the potential difference between two points imparting one joule of energy per coulomb of charge that passes through it. Following Ohm’s law, the volt is defined as the current flowing multiplied by the resistance.

What properties of the material influence the flow of the electron?

As stated above, the mobility of an electron depends on the material and how the electrons are held with the nucleus of the element, i.e., loose or strong bonding. In metals, electrons are held loosely; such material is called conductors, and when held firmly, is called insulators.

What is Ohm?

This material property has led to defining the term ‘Resistance’ with the unit as Ohm (symbol Ω), named after the German Scientist George Simon Ohm. George Ohm did his work measuring the flow of current with varying voltage and derived the relation between voltage, current, and resistance and the influence of temperature. He also studied the influence of the cross-sectional area and the length of the wire in the flow of charge. Resistance is the property of a substance due to which it opposes (or restricts) the flow of electrons (or current) through it.

Which are good conductors of electricity?

Those substances with loosely held electrons and offer the least difficulty in the mobility of electrons are good conductors of electricity (and even heat). Metals (as a class), acids, and salt solutions are good conductors of electricity. Amongst pure metals, silver, copper, and aluminum are good conductors. These electrons, while flowing, find obstruction by the nucleus and other electrons, collide and thereby loses energy and appear as heat.

Which are the bad conductors of electricity?

Those substances with strongly held electrons that offer greater difficulty or hindrance to the passage of these electrons are said to be relatively poor conductors of electricity, like Bakelite, mica, glass, rubber PVC (polyvinyl chloride), dry wood, etc.

A good and bad conductor both have an application in electrical engineering since it will require free and restricted movement of electrons depending on the requirement. The research work of Ohm was associated with a direct current of the battery. Still, today, it fits equally for an alternating current circuit (sufficiently complicated as compared to direct current) and magnetic circuit with ‘mmf’ equivalent of ’emf’ and ‘magnetic flux’ equivalent to ‘current.’

How the Electrical Engineering take shape in subsequent years?

Scientists, engineers, and innovators found electricity most useful in the service of humanity. They worked continuously in all areas of making the electron flow a carrier of energy and utilizing it wherever or whenever required. It is possible to control, restrict, stop and reverse the flow of charge, which results in the developing of various areas of Electrical Technologies. Some of the areas are as under:

  1. Sources of energy and converting into electric energy: Battery/Solar/Wind/Hydropower or Waterhead/Coal base steam turbine-Generator/nuclear energy base generator/geothermal energy etc.;
  2. The flow of current (or charge or electron) is controlled with the help of material such as an insulator, conductor, semi-conductor, etc. Using high-speed gates either to pass or stop the flow of electrons with the help of semi-conductors devices;
  3. Transmission of electricity to far-off distances at higher voltages using the transformer, HV DC Transmission, HV insulators, conductors, etc.;
  4. The utilization of electric energy in industry, house, and commercial activity;
  5. Electrical Safety;
  6. Transportation- electric traction;
  7. Electrical devices – motor, heating, illumination; and
  8. Electrical Measurements and Instrumentation.

Conclusion

One can understand any complicated function of electricity by studying the behavior of electrons or charges. We should pay our tribute to the painstaking, methodical, and intelligent work of all those great scientists, innovators, and mathematicians who helped develop this great subject. The four great scientists who were honored for their contributions and seeing the issue from their perspective make the subject of electrical engineering much more simplified.

The Electrical Engineers salute you for your contribution toward the betterment of mankind.

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