Electronics Tutorial: Current, Voltage, Resistance

Intro

This post will attempt to introduce you to the basic concepts that make electronic circuits tick. Hopefully, the basic knowledge from this post will help you understand more complex concepts down the line. This post is not for you if you already have a grasp of the basic concepts of current, voltage, and resistance. I will attempt to introduce the basics without getting into complicated science and maths unless it is otherwise necessary.

Without further ado, let’s jump on in and explore the basic science behind electronics.

Electricity

You might know that matter is made up out of atoms. Atoms are of the basic building blocks of everything that exists and a bit of knowledge on how they’re made up will help with understanding electronics too.

Atoms are primarily made out of a nucleus, containing protons and neutrons, that is surrounded by electrons. Electrons exhibit a negative charge. A particle’s charge determines how it is affected or affects other particles in electromagnetic interactions. Particles with the same charge will repel each other, and those with different charges will attract each other. When an object has an excess of electrons, it is negatively charged. Thus, a shortage of electrons will make something positively charged. This is a very basic and simplified abstraction of atoms. The reality of the subject matter is more complex but the basic idea of electrons as a particle works with the basic understanding of electronics.

When an object’s surface contains a charge (such as an excess of electrons) it can be called static electricity. The electrons and charge aren’t (yet) moving anywhere. The charged surface exhibits an electrical field that attracts or repels other charged particles. Actually, it’s the particles making up the charge that exhibit this electric field. This can be demonstrated by holding a charged hair comb next to a fine stream of water. The static electric charge of the comb will cause the flow of the water to bend.
When given a path to move, the electrons on the charged surface will be able to move and will tend to neutralize the charge of the object. It will move from a majority negative charged area to a more positively charged area.

We can measure charge. The standard unit for charge is the coulomb. It is determined that 1 Coulomb is equal to approximately 6.242 × 1018 electrons. That’s, like, a six with 18 zeros attached. The actual number of electrons (or protons for that matter) in a coulomb isn’t that important for hobby electronics. The coulomb unit, though, is used when explaining current or capacitance so it is good to mention it here.

When electrons move, we have electrical current.

Current

Electrical current is when electrons are moving in a conductor. Electrons tend to move from a negatively charged area (repel electrons) to a positively charged area (attract electrons).
A popular analogy for current is that of the flow of water in a pipe. Similarly, the electron current is said to be flowing in the conductor “pipe”.

More often than not in hobby electronics, we don’t talk about the movement of electrons, we talk about conventional current. Conventional current is the flow of positive charge. Even though it is actually the electrons that are moving, conventional current is said to be positive charge moving from a positive area to a negative area.

Current can move continuously around a circuit in a manner called direct current, abbreviated as DC. This is what is mostly used in electronics and is the type of current supplied by batteries and lab power supplies.
The other way for current to move is to-and-fro in the conductor, continuously going forwards and then backward and then forwards again. This is alternating current abbreviated as AC. This type of current is generally used to power home electrical appliances. AC is also used in electronics in, for example, radio transmitter circuits. It is thus a good idea to know a bit about AC as well as DC when learning about circuits.

Current is measured in amperes. It is said that one ampere is equal to the movement of one coulomb of charge in one second (told you coulomb will be mentioned again).

Up next we’ll find out, basically, how we can cause charges or electrons to move and create a current.
Click through below to the next page to continue this tutorial on basic electronics.

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