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3 Basic Engineering Quantities You Should Know

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electrical-engineering-quantities

Electrical engineering isn’t as hard as people show it. Here you can understand electrical engineering with just three basic engineering quantities. So, let’s get to that

Electrical engineering is one of the most demanding yet complex engineering fields. Electrical engineering isn’t just specified to electric, instead, you get the exposure of the construction sites, manufacturing sites, design companies, and whatnot. 

 In short, every department that intends to have machinery or other electrical/electronic equipment has the need for an electrical engineer. Yes, here we stand; in every department of every field you will always find an electrical engineer holding the company’s main assets in hands. 

Engineering is something that demands through understanding. The learner should know the basics in order to go high in the field. 

If your teacher ever said the words “As you already know” and you realize that you actually don’t know because nobody finds it important enough to discuss, then you have come to the right place. 

The three quantities that you should know in depth are 

  • Current
  • Voltage
  • Power

Before plunging into the 3 basic quantities, first understand the charge as a property of current. 

Charge

When I was a kid, I always had fun rubbing dry comb in my hair. Did you try it? To understand better about this short fun activity you should know about an atom.

An atom contains charged particles: positive protons and negative electrons. Generally, there is an equal number of protons and electrons; the net electric charge of the atom is 0.

As the name suggests, “Electrostatic,” which means charges at rest, and if charges start flowing, then it will produce electricity.

charges-comb
A fun activity of my childhood where I used to rub my dry comb in my hair and paper starts attracting towards it.

This has proved to be the most fun activity in my childhood. You rub your comb on dry hair, and then the paper starts attracting towards your comb? It is because of the electric charges. Paper won’t attract the comb until and unless you rub it on your hair because they were neutral before. As the law of gravitation suggests, every other thing attracts each other, but they don’t have much force to attract it. We have provided the force of attraction, and it has charged through rubbing.

Like and unlike charges

Two positive or two negative charges repel each other; a positive and a negative charge attract each other.

We can’t say what electric charge is; we can only describe its properties and its behavior.

Current

In the last heading, we examined the link between an atom and a charge. In this heading, I would like to inspect the early days of the current.

During the early days of the 19th century, scientists had only been able to generate static charges, which couldn’t be much to create a constant spark. Italian scientists, Alessandro Volta, invented the first voltaic cell. The batteries we are using in 2020, still running on the same principle as a voltaic cell.

circuit-of-a-light-bulb
A circuit of light bulb

So far, you understand the early days of current. Let’s get deep into the current. What is a current? Current is the flow of electrons or the amount of current passing through a wire over some time. Energy has been provided in terms of voltage, like electrons, from one point to another. 

Usually, current flows from higher voltage to lower voltage. For example, like river water coming from the top of the mountain and going into the stream, but we need electrons to make it flow continuously.

Voltage

There are many other ways to define voltage, but the simplest, yet easiest way to define a voltage is the difference between electric potential from one point to another.

You might have read the definition of a voltage. Let’s discuss the definition of electric potential. Electric potential is the work needed to move an electrical charge from a reference point to a specific point.

Historically, words like “tension” and “pressure” are still using for voltages, and you must have heard about the high tension cables; it carries more than 1000 volts between conductors.

Voltage can be measured through ohm’s law;

Voltage = current*resistance or V=IR

Where,

V is the voltage

I is the current

R is the resistance of the conductor. 

Voltage across inductors

Previously, we talked about the definition of a voltage. In this heading, I would like to explore how we could measure the voltage across inductors. Inductors can be used in multiple ways according to their needs and requirements, from automobiles to delivering powers. 

Mostly, inductors are used for blocking, choking, filtering the signal, energy storage device, and they are also used with capacitors and resistors to create filters. 

The voltage across the inductor is directly proportional to the rate of change of current. It can be measured with the help of a formula:

V=L di/dt

Where,

V is the instantaneous voltage across the inductor

L is the inductance in Henrys

Di/dt is the rate of current change   

voltage-across-inductors
source: https://courses.lumenlearning.com/physics/chapter/23-11-reactance-inductive-and-capacitive/

Measuring tools

a-digital-multimeter
A digital multimeter

To measure the voltage, we could take advantage of voltmeters. Voltmeter could be analog or digital; analog voltmeter has a pointer at the screen and moves according to the voltage in the circuit. A Digital voltmeter gives a more accurate value than an analog voltmeter. 

You might have seen a gadget in your electrician’s hand, which is a multimeter because it can be used in either AC or DC. You just need to move the probe giving on a multimeter to AC or DC.

Voltage, current and Resistance Analogy

Voltage itself is such a big topic and we can’t understand through only the definition. Let’s discuss the analogy for a better understanding. We could also define voltage, current, and resistance with the water tank analogy where water is the charge, voltage is the water pressure, and current is the flow of water.

current-voltage-Resistance-analogy
Source: sparkfun

If we compare this water tank with our battery, as the quantity of the water increases; so does the charge, and if we let water out from the tank means the voltage is decreasing. For example, your flashlight gets dim and dimmer as the day passes by, so in this case, you let the water out; it means a decrease in voltages.

Power

It is the rate at which electrical energy is consumed in an electrical circuit. It is measured in watts, named to honor James Watt. The SI unit of power is watt, which is joule per second. There are three types of electrical power in AC

  1. Apparent power
  2. Real power
  3. Reactive power

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