The electricity is the set of physical phenomena associated with the presence and movement of electric charges, and it will be the foundation of everything we see in this course.
Before we dive into formulas, circuits, motors and other paraphernalia, it’s worth starting from the beginning. Because we all use electricity every day, but we don’t always have a clear idea of what the hell it really is.
Electricity is in the light at home, in your phone charger, in the computer, in a battery, in a motor, in a resistor that heats up, and in a high-voltage power line. It is so common that we almost don’t see it anymore.
And precisely because of that, we sometimes forget that behind it all there is a very simple yet very profound idea: matter has an electric charge, and that charge can exert forces, move, store energy, and transfer it from one place to another.
Don’t worry if this sounds a bit abstract now. In this first part, we’re going to take it step by step, building the foundation from scratch.
What is electricity?
The good news is that, unless you’ve been living in a cave for the last two centuries, you already have a pretty good intuition about electricity. You know it can light a bulb, spin a motor, heat a resistor, or fry a component if you connect it where it doesn’t belong (which is also a very traditional way to learn).
The bad news is that if we wanted to describe its ultimate nature with all possible rigor, we would have to talk about quantum physics, fields, particles, electromagnetic interaction, and a few other things that would take us well beyond the scope of this course.
So let’s make a reasonable deal. In this course, we will focus on classical electricity, which is the model that allows us to understand and calculate the vast majority of real circuits, installations, machines, and electrical systems.
Electricity allows us to transport, transform, and harness energy through the behavior of electric charges.
This does not mean we will learn recipes without understanding anything. Quite the opposite. Whenever necessary, we will go down a level and see what is physically happening so that the formulas make sense.
Electricity is not the same as electronics
Before moving on, it’s worth clearing up a fairly common confusion. Electricity and electronics are closely related, but they are not exactly the same thing.
Both work with electric charges, voltages, currents, and energy. The main difference lies in what we use these phenomena for.
Electricity focuses primarily on energy. We are interested in generating, transporting, transforming it, and converting it into useful work, such as motion, heat, or light.
Here we care about things like power, losses, cable sections, transformers, motors, or electrical safety.
Electronics focuses primarily on information. We use electrical signals to measure, control, communicate, process data, or make decisions.
Here, precision, speed, noise, semiconductors, and the behavior of active components matter a lot.
Of course, the boundary is not always perfect. A variable frequency drive, a switching power supply, or a battery charger have quite a bit of both. Reality usually doesn’t respect our mental folders, because that would be too easy.
In this course, we are going to start with classical electricity, because it is the foundation upon which everything else rests. If you understand charge, voltage, current, energy, and power well, then electronics becomes much less mysterious.
If you already know the fundamentals of electricity and want to learn about electronics, take a look at:
What we will learn in this course
Electricity is one of those topics where it is worth building knowledge layer by layer. If the foundation is weak, formulas will later appear as if pulled out of a hat.
In this course, we will progress from the most fundamental concepts to more complete electrical systems:
- Nature and physical quantities: We will see what electric charge, electric field, potential, voltage, current, and energy are.
- Direct current circuits: We will work with Ohm’s Law, Kirchhoff’s laws, resistors, dividers, Thévenin and Norton equivalents.
- Electromagnetism and induction: We will see the relationship between electricity and magnetism, which is certainly no small matter.
- Alternating current: We will talk about sinusoidal waves, frequency, phase shift, impedance, active, reactive, and apparent power.
- Machines and power systems: We will finish with transformers, motors, three-phase systems, and basic concepts of electrical safety.
The idea is not to memorize formulas like a parrot. The idea is to understand where they come from, when they can be used, and what they mean physically.
The origin of everything
If we have to choose a starting point for understanding electricity, that point is electric charge. It is a fundamental property of matter, just like mass, although quite less intuitive at first.
From this property come forces, fields, potentials, currents, batteries, generators, motors, power lines, and virtually everything we will see during the course.
In the next entry, we will start precisely there: electric charge and the electron. We will see what it means for a particle to have a charge, why electrons are so important, and how something so small ends up moving things so big.
Let’s get to it!
