Electrical Theory – A Basic, Metaphoric View (Part 1)

Some things I plan on writing for this site require a basic understanding of electrical theory. For example, if I talk about a “voltage drop” across a circuit component, the reader must have some sense of what the term “voltage” means. Or, if I describe an electrical component that “draws 2 amps,” it would be nice if the reader had a sense of what is meant when someone talks about electrical current. Of course, if you have some basic understanding of these concepts, feel free to stop reading this post now and possibly find a more fun post about old engine ignitions, or the odd refrigerator problem I once discovered (these two topics will be addressed at some point).

I also would note that I am not a physicist, or a scientist of any kind. That is to say, I’m a dabbler at best and anything I describe here will not be rigorously laid out. I am not going to talk about the underlying physics of electrical theory, the behavior of electromagnetic fields, or the quantum properties of electrons. I will simply be attempting to describe the basics of “electricity” as I understand them in a very imprecise (often somewhat incorrect) metaphorical way. This metaphoric approach has been carried out many times all over the internet (and in other places, such as over coffee and a toasted muffin in a small shop somewhere) with varied success.

I suspect purists get very angry at the metaphoric “imagine an electron is a ball” sort of description, as an electron is not a ball (according to my physicist friends), but I do believe that a coarse view of the world can allow a person to start understanding the ways of nature and then, depending on their inclination, dive deeper into a more precise view. The coarse understanding of things also provides the “layperson” a sense of agency – that is they can begin to understand and possibly have some control of things around them that were previously out of reach and uncontrollable. Further, a basic possibly imprecise understanding of something provides a sort groundwork allowing discussion of topics that were otherwise undiscussible prior to this roughshod sort of knowledge.

One might also ask: If this coarse approach of electrical metaphors has been laid out many times before all over the internet and also over coffee and muffins, etc, then why would you do it again here? And my answer would be (and is): Because maybe my take on it will spark an understanding in someone that other explanations did not. Or maybe it wont… At any rate, I will strive to be concise in my half-baked wanderings below – something I failed to do in this introduction above.

Now… forget all about electricity! and imagine a ball…

… possibly a tennis ball, or a bowling ball or a blob of snow that you rolled into a somewhat large ball as a child. I will quickly note here (to avoid further angering the purists) that I am ignoring the details of friction and huge swaths of basic high-school physics as I deal on this topic. But, BACK TO THE BALL… So you have this ball (snowball from now on) and it’s laying on the cold sidewalk and you push on it. When you do that, the ball starts to move. That’s right, move. This implies that it was previously traveling at zero miles per hour and now it is traveling at some miles (or fraction of) per hour.

The ball had to get from zero to some speed greater than zero, which implies it accelerated. Its speed changed over time – it didn’t just instantly go from zero to a faster final speed – its speed (or velocity) ramped up over time. What I am trying to lay out here is that when you apply a force to a body (such as the ball), it accelerates. Also, if you see something accelerating (such as a car at a drag strip or a person diving off a diving board towards some water) there is a force acting on that something. In the case of a car, the force is provided by the engine. For the diver, the force of gravity would be the likely culprit. In the case of your snowball, the force was provided by you (or the child you if you now have given up on pushing giant snowballs).

Similarly, with electricity you have small particles that accelerate too. The acceleration of these things is due to a force, and the size of that electrical force is described using the term: voltage. It is important to know that the voltage is just a word – it is just the word that was assigned to describe electrical force.

Now, a voltage acting on certain types of particles will cause those particles to accelerate in space (i.e. the physical world around us, not just “outer space” although these forces work there too). This voltage is in some sense equivalent to the force you applied to the ball I described above (snowball, etc). You applied some pressure (another word describing a type of force) to the snowball and it accelerated. When a charged particle accelerates, it is experiencing an electrical force (voltage).

The terms pressure and voltage also have associated units, which describe an amount of force. With pressure, the units might be pounds applied over an area of the surface – like “pounds per square inch” (psi). With voltage, the unit is simply “volts,” and all you really need to have is a relative understanding of this unit. That is, that 10 volts is 10 times more electrical force than 1 volt, for example. Another way to think about this is that 10 volts will impart 10 times the acceleration on an electrical particle that 1 volt will impart. So, if you are at a drag race you want to bet on the 10 volt car not the 1 volt car.

Now imagine…

that you have a friend (I hope you do) and your friend is standing next to you, and you both have (equal sized) snowballs in front of you. You both start pushing them with the same force at the same time. Then what? Well, you have two things accelerating down the sidewalk! Now let’s say your sister and her friend have built two igloos next to one another down the sidewalk from where you and your friend are pushing the snowballs. Because you and your friend are mean, you smash into both their igloos destroying them (later you both apologize and get them hot chocolate). If just you were pushing a snowball, you could have only destroyed one igloo, but because you and your friend were pushing them, you destroyed two! Yes, you did twice as much work as just one of you could have done!

Now, back to the electrical comparison and a new property (current): The amount of moving electrical particles in a system is described by the term current – just like counting the number of snowballs moving towards the igloos. Again, current is just a word that was chosen to describe this property (nothing mysterious or magical about it). Current is a different thing than voltage. Where voltage describes the force on a particle, current describes the number of particles traveling during a period of time. This Current is often described as the rate of electrical charge (the amount of particles traveling per unit time). It’s kind of like if you stood at the side of a road and counted the cars that drove past in a specific amount of time. Say, in ten minutes you could count one car, or ten cars (or more). The number of electrical particles that pass a certain point in a set amount of time is described by the term: “current.” The unit of current is the “ampere” or amp for short. Quickly, back to the snowball analogy: If just you were pushing your snowball, that would be a certain amount of current (metaphorically). If you and your friend are pushing snowballs at the same time, that would be twice the current as when it was just you.

Combining these properties: Voltage and Current

Electrical particles are quite small (more specifically on these particles in part two of this post). One of these particles doesn’t make much of a dent at the scale we observe daily (i.e. Our world of dinner rolls and sneakers, etc). So, if you applied some amount of force (voltage) to just one of these particles and fired it at someone, they would likely not even notice. But, if you applied that same amount of force (a voltage) to large numbers of these particles all at once so they all flowed together (i.e. higher current – the rate of flow – measured in amps) and hit someone with them, this forceful blast of particles could do a lot of damage – think lightning bolt damage.

Alternately, you could fire half the number of particles in a given period of time (less current) with twice the force (double the voltage) and do the same amount of damage. The point is that these two properties (volgage/force) and (current/amount per unit time) are needed in combination to understand how much work you can do. Neither of these terms individually really gives you sense of how much work is done, but when both are known you do know how much work the electrical particles can accomplish (i.e. how many igloos can be knocked down in a period of time). This concept of work is important, as we (and the Universe) is always getting things done (doing work) and when the work is electrical, the whole picture must be described using the combination of these terms (voltage and current).

More is needed…

In part two, I will (slightly) more formally describe the relationship between voltage and current, describe what a bit more about charged particles, and how these particles “flow” (or really don’t flow that much). Again, the idea with all this is to allow basic discussions of simple electrical circuits and circuit components. For example, what is a capacitor and what does it store? What is an inductor? Why might a motor have a “start capacitor”? How is an inductor used to create a spark in a gasoline engine? Why did the motor relay in my dryer overheat and melt the circuit board it was soldered to? None of these topics can be discussed without some basic understanding of electrical concepts. More is needed in this area, but hopefully the explanation thus far will be helpful to some. We are on our way.

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