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Help understanding basic electricity

Guest ElyxR

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Guest ElyxR

Hi FizziksGuy,

As you may remember from about a day ago I posted a msg on youtube for your clip entitled: "High School Physics: Electric Charge".

I'm the guy that's struggling with physics even after so many years (say, 30 or so).

If you don't mind the rather long read in this post, I'd like to give you a backgrounder to why I've ended up here, and some relevant checkpoints along the way. At the end of this post I will post my question and depending on your response (or on whether you're still willing to respond :) ) this will shape what my next question will be; because no matter what attempts I make at having electricity as a whole explained to me it seems to never address my questions and lack of understanding; so I've taken to asking specific questions instead in the hope that this will actually work for me.

It's okay if you take.. days to respond, because I don't want to take up your time with your students.

Back then in 1984 and 85 we didn't have the internet and if I needed the extra information I could stay after class, go to the library, etc.

But unfortunately, the learning format of having things explained to me over and over again with slightly different twists, even across many years, had no effect.

As you may recall my mentioning on youtube, I ended up retaking my electricity class, twice, back to back so that I could complete my last, and first-to-last year of obligatory school. I think in many places it's called grade... 12? 13? For me, back then, in Montreal, it was called Secondary 5.

I was pretty dismayed back then because I excelled at almost every topic. I got near 100% grades in chemistry, mathematics, computing (in its infancy back then) and in the rest of my physics class as well, and I failed (below 50%, back then) electricity.

Now here's the thing: I didn't excel because my parents wanted me to, I didn't excel because I wanted good grades, I didn't excel because I wanted to impress a girl...I didn't excel because I had no other life...

I excelled because I was fascinated, curious and passionate about life around me and about how our world works; and I still am today.

I remember times at home or sitting at my desk after class with a blank stare and wondering why. Why am I not understanding this thing? Pretty much everybody else seemed to be getting it so it must be an achievable goal. So why oh why?

Just recounting you these memories is enough to bring back the sense of frustration I had of not understanding electricity. If anybody wants to know what that's like just try to learn juggling (that's another one... I will juggle one day... Guaranteed).


Fast forward many years; I have a family now, a career, a home... That came with an unfinished basement.

We decided to finish our basement and I was all primed up to tackle this project on my own, instead of hiring professionals. So I designed everything: Location of the walls, kind of floor, type of ceiling, location of electrical outlets.. pot lights, brightness, recessed or not, dimmeable or not... That I could control from different locations...

And TADA! After 30 years of avoidance; I finally had to face my nemesis: Electricity.

I abandoned many projects across the years, or potential projects, because they involved electricity; but this one I couldn't avoid/didn't want to avoid.

Long story short: I got through it by breaking down each part of my design into manageable, individual chunks and by seeking a lot of highly targeted pieces of advice. I was then able to get the electricity part of the project to work but did I really understand what I was doing with the electricity part of it? Hell no.

Already at that point I thought that I had to up my game, I had to understand electricity once and for all; but I let it go. Project was done, life goes on. I moved on.

And finally about 6 months after that. I had another one of my brilliant ideas when, after having had an electric motor installed for my garage door (by a third party) I would find the said door somehow opened every now and then, without my knowing it. I thought hey, why don't I just build myself a simple circuit that will light up a tiny light in my hallway (inside the house) when the door is opened !

I thought, hey, let's even make it an LED since it's such a low power item apparently... So I'll only need a few batteries.. And they'll last a long time... etc..

Well as you may already know, LEDs are a pretty peculiar bunch of devices, compared to incandescent lights and they have their own way of working with electricity. Since I was going to order the items online myself, I had to know exactly what to order... And in order to do that I had to have a real hard look at the specifications for LEDs and what I found, I, once again, could not understand at all.

So in that case what I did was build my circuit with what I thought was my best guess, based on info I pulled together left and right I built the thing and it looks and works real great actually and but then, one day, maybe just 7 months after setting the whole thing up the batteries died.


According to my best guess the batteries (2 x AAs) should have lasted me a couple years because the circuit was only closed when the door was opened. The door was opened probably the equivalent of only about 30 hours during those 7 months. And either way, according to a longevity test that I had run prior to setting up my circuit, I found out that If I hooked up one LED directly to 2 AA batteries, non-stop, day and night, lighting up the LED 24/7; well it took about 3 months of powering the LED non stop before the batteries died... So why were my 2 AA batteries, from the same pack of 8, that only powered the LED every now and then, would be drained 7 months later?

At this point I decided that I had enough of winging it. I had enough of best guesses and I was going to understand electricity once and for all.

After watching many clips of all sorts (including black and white ones from like the 40s !), reading countless articles, going around in circles in Wikipedia - and all of this over many months - I think I may have finally narrowed down what it is that I do not understand.

The water analogy to understand electricity, does not work for me, I zone out when I hear it because saying that either volts or amps or whatnot are like water pressure does not help in my case because I don know what volts are at a low level to begin with.

The formulas don't help either because I don't know what the essence of the things that I am multiplying and dividing is/are.

But, TADA! I watched your clip and here we are...

Electrical Charge.

The most basic of charge(s) (quantas excluded), correct?

It is the charge held by one electron (and proton), correct?

One coulomb, is a bunch of electrons that each have one electric charge, correct?

A coulomb is actually equal to 6.2415~×10 to the power of 18, electrons, correct?

If that is all correct, then I'm down with that. I totally get that. This actually speaks of things I do understand. In a way that I can understand.

Can we take this knowledge and build it up to the point where it correlates (for me) to what happens a few levels up? Say, at the level of a simple cell/battery?

For example, let me ask you this:

Let's say that I have one tiny, tiny piece of metal, and that this kind of metal happens to be made up of atoms that each have one free electron. Let's further say that there happens to be 6.2415~×10 to the power of 18 of those atoms; and finally let's say that this piece of metal is just lying there on my computer desk, doing nothing; my question is, can I say that I have one Coulomb worth of electrons?

I mean, there's no electricity, I think, because there's nothing for those electrons to interact with but still.

Actually, I guess I can even ask you this: Does an electron have an electric charge even though it is not in a situation of difference of potential with another particle (proton, probably) somewhere else?

Once I have your response, I will know what question to ask next.

Thank you very much for your time.

Edited by ElyxR
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Wow, great questions ElyxR!

I love it when folks want to genuinely UNDERSTAND, not just learn enough to pass the test. And it sounds like you're doing pretty well so far -- and I agree, voltage / potential difference is one of the hardest parts of electricity to truly understand -- I certainly didn't "get it" my first, or even second, time through. And I'm still learning more each time I teach it.

So, let's get down to your questions. The charge on a single electron is -1.6x10^-19 C, or, put another way, 6.24x10^18 electrons would give you -1 coulomb of charge. Correct.

That piece of metal on your desk, yes, you could say you have 1C worth of electrons, although it's not a very meaningful statement. For charge to be useful, you're usually looking at NET charge. For example, if you have an electron and a proton, with charges of -1e and +1e, respectively, overall you have a net 0 charge. When things get interesting is when you have an imbalance of charge... extra electrons (negative charge), or lack of electrons (positive charge).

And yes, the electron has that charge even though it is not in a situation of potential difference with another particle somewhere else. Charge is a fundamental property of that electron. You can't have an electron without having a charge of -1e.

Hope that gets you started!

(by the way, scientists later learned that you can actually have charges smaller than 1e, when you start getting into sub-atomic particles such as quarks -- you can learn more about it by watching the "Standard Model" video, but for your current goals and all practical purposes, it really doesn't make a difference at this point!)

Make it a great day!

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Guest ElyxR

FizziksGuy thank you very much for your response!

It's good that this confirms for me that question I had about the coulomb.

Ok let me ask you this then:

Still dwelling at that low level of electricity, talking about my piece of metal on my desk and considering your response, would it be correct to say that:

- It has a charge of one coulomb but no Net charge?

- That piece of metal can only have a Net charge in relation to another object?

- Net charge means the same thing as Potential difference?

Here are other questions I have about that piece of metal:

- What are the electrons doing on that piece of metal, they're only doing circles around the nucleus of their respective Atoms, correct?

- Furthermore, they don't happen to be jumping around somehow between any one of their neighbor's Atoms in anyway because since I have designed that piece of metal to only be made of identical Atoms that all have one free electron, there is no room for any electron to go anywhere, correct? Assumptions being made here that there doesn't happen to be any other exterior influence or force meddling with the said piece of metal, aka, we're in a vacuum.

I'm not sure how to ask my next question, so here's what I came up with:

- What would be the most basic Atom in existence (or element) that befits my design? I mean my design was 1 Atom that had one free electron. Understood here that any Atom that has an excess of 1 Electron would fit the bill but what would be the most basic one, Hydrogen ion?

I say that because an Hydrogen Atom has 1 Electron going around a nucleus made up of 1 Proton and 1 Neutron. But that electron isn't free, correct? If I wanted that most elementary element (struggling for words here), Hydrogen, to have any electric charge, wouldn't I need to either knock off it's electron, giving me an excess of 1 Proton, thus giving it a positive charge, or knock off it's proton, giving me an excess of 1 Electron, thus giving it a negative charge?

I guess I can even ask, is it even possible to have an Hydrogen atom with NO electrons? Only its nucleus of 1 Proton and 1 Neutron?

Inversely is it even possible to have an Hydrogen atom with NO Protons? Only a nucleus of 1 Neutron with en Electron going around it?

If such an Atom would be possible, would it even be called Hydrogen anymore?

Would it even be called an Atom anymore?

Please bare with me as I try to iron out these basic concepts first before I jump to the crust of electricity as it pertains to circuits etc..

Eagerly awaiting your response!

Edited by ElyxR
Clarification, sentence structures.
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Good Afternoon,

Yes, you could say the atoms have an electron charge of -1C, the protons have a charge of +1C, therefore there is no net charge.

A piece of metal can have a net charge on its own. For example, an atom (ion) with 4 electrons and 3 protons has a net charge of -1.6x10^-19 C.

Net charge and potential difference are quite different critters.

What the electrons are doing is actually a very complicated question. Electrons around an atom are represented as being in a "cloud" of probable locations. Strangely enough, in a short enough time interval, that electron can actually be in more than one place at a time! As you get into the physics of the very small and very fast, life gets weird in a hurry.

Best atom for you to start with would be hydrogen. If I can, I'll refer you to the Models of the Atom tutorial. If you start with hydrogen, it can pick up an extra electron to become a hydrogen ion (-1e), or it can lose its electron to become a hydrogen ion (+1e). If it were to lose its proton, it wouldn't be hydrogen anymore.

Yes, you can have a hydrogen atom with no electrons. Lose the proton, though, and by definition it's no longer hydrogen.

This may also help you in your quest to understand electricity: http://www.aplusphysics.com/courses/regents/electricity/regents_electric_charges.html

Good luck!

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  • 3 weeks later...
Guest ElyxR

Hi there FizziksGu, how is it going?

It took me a while longer than I thought it would in order to respond but I think I finally am able to.

Also I did watch the clips you suggested and they were a bit helpful.

I like your idea of using the Hydrogen Atom to help me understand Electricity so let me ask you:

- An Hydrogen atom, in its purest form, has no charge?

- If I have 6.24x10^18 Hydrogen Atoms, and given that each Hydrogen Atom has one Electron, I therefore also have one Coulomb of Electrons?

- However, since I don't have any excess nor lack of Electrons I therefor have no Net Charge?

- However, I do have a potential difference and it is of 1 Coulomb?

Once I've confirmed that I will be able to move on to my next questions.

Thank you,

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