The irony is I clicked on 2 links on this site and left because it's not user friendly
Why is electricity so hard to understand? (1989)
41–50 of 216 posts
Re: Why is electricity so hard to understand? (1989)
#42I think more than half the time I spent earning my EE degree has been spent unlearning the intuitive (but wrong) things that I was liberally taught. I was fortunate enough to have an exceptional Physics teacher in high school, who managed to avoid a lot of the bullshit that less fortunate students were fed; sadly, I compensated that with some of my own (misguided) self-study. This experience also taught me to activel…
I got it taught about 3 or 4 times, and every time I understood it less. In middle school they told me, it's electrons moving at the speed of light through a conductor. In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. At…
The first chapter explained it well.
There are three different concepts that were all thrown under the umbrella term "electricity".
>..little use by educators of the wind/sound electrical analogy:
>AIR is a physical substance.
>SOUND is a wave that propagates rapidly through a volume of air.
>WIND is a flowing motion of air already present.
>ELECTRIC CHARGES are a physical substance.
>ELECTRIC ENERGY is a wave that travels via a column of charge.
>ELECTRIC CURRENT is a flowing motion of the charge already present.
Re: Why is electricity so hard to understand? (1989)
#43I think more than half the time I spent earning my EE degree has been spent unlearning the intuitive (but wrong) things that I was liberally taught. I was fortunate enough to have an exceptional Physics teacher in high school, who managed to avoid a lot of the bullshit that less fortunate students were fed; sadly, I compensated that with some of my own (misguided) self-study. This experience also taught me to activel…
I got it taught about 3 or 4 times, and every time I understood it less. In middle school they told me, it's electrons moving at the speed of light through a conductor. In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. At…
As far as circuits go, this is about the closest high school Physics gets to truth (and it's decently close, compared to how wrong it gets e.g. capacitors):
> In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light.
although "entering" and "exiting" the conductor isn't really a good description.
A better way to think about it is that "conductor" is really just slang for "material that has a bunch of free electrons and very little room for more". This is the "sea of electrons" that Beaty talks about. It makes sense that, if all this sea flows steadily (i.e. at the same rate throughout the conductor), forcing a change in the rate of flow in one part of the conductor will be felt almost immediately in another part of the conductor, no matter how distant, even if the flow itself is extremely slow.
(If you're thinking that this is only true if the "pipe" through which the "sea" flows is full, you're right, this is how free electrons behave in conductors; that's why Beaty insists that a good analogy for a conductor is "like a pipe which is already full of water".
> At university they told me, no no, you got it all wrong, it's about the electro static and electro dynamic fields which stand orthogonal on each other and produce electro magnetic waves... what?!
If they taught you that, they are most definitely wrong, it sounds loosely like induction, but with two strange names instead of "electric" and "magnetic" :-).
This is a better description of the physical reality, and it does help you understand circuits better if you think about it, but not in a very practical manner.
Re: Why is electricity so hard to understand? (1989)
#44The real question is, why is this website so hard to understand? Publishing what looks like someones personal notebook isn't helping the cause here.
Poor selection of link. Fortunately the author saw us and pointed us toward the articles instead of the raw notes: http://amasci.com/miscon/whyhard1.html#def
Re: Why is electricity so hard to understand? (1989)
#45I think more than half the time I spent earning my EE degree has been spent unlearning the intuitive (but wrong) things that I was liberally taught. I was fortunate enough to have an exceptional Physics teacher in high school, who managed to avoid a lot of the bullshit that less fortunate students were fed; sadly, I compensated that with some of my own (misguided) self-study. This experience also taught me to activel…
I got it taught about 3 or 4 times, and every time I understood it less. In middle school they told me, it's electrons moving at the speed of light through a conductor. In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. At…
Your last two answer are the same. It's just that the last one is much easier to calculate.
Re: Why is electricity so hard to understand? (1989)
#46Wires may not be hollow tubes but surely as a EE he knows that most current flows through the outer shell of the wire? E: Yes, I was thinking standard AC for household appliances, my bad
What kind of current are you putting into them? And what kind of wires?
For DC, no it does not.
Re: Why is electricity so hard to understand? (1989)
#47Earlier quoted context omitted.
The issue with chemistry is that you need to develop a "feel" (chemical intuition) for a lot of topics. A lot of chemistry taught in undergrad, like Organic, cannot always be neatly explained or solved with an equation. On top of that there seems to be as many exceptions to rules as there are rules themselves.
A lot of stuff taught in undergrad is also flat out wrong, especially anything to do with orbitals.
What aspects of orbitals do they get wrong?
Re: Why is electricity so hard to understand? (1989)
#48Earlier quoted context omitted.
I got it taught about 3 or 4 times, and every time I understood it less. In middle school they told me, it's electrons moving at the speed of light through a conductor. In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. At…
As far as circuits go, this is about the closest high school Physics gets to truth (and it's decently close, compared to how wrong it gets e.g. capacitors): > In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. although "en…
> If they taught you that, they are most definitely wrong, it sounds loosely like induction, but with two strange names instead of "electric" and "magnetic" :-).
I don't think "definitely wrong" is a good description. electrostatic and electrodynamic are perfectly good, if somewhat archaic, terms for the electric and magnetic fields. (E and H fields)
Re: Why is electricity so hard to understand? (1989)
#49I think more than half the time I spent earning my EE degree has been spent unlearning the intuitive (but wrong) things that I was liberally taught. I was fortunate enough to have an exceptional Physics teacher in high school, who managed to avoid a lot of the bullshit that less fortunate students were fed; sadly, I compensated that with some of my own (misguided) self-study. This experience also taught me to activel…
From the linked notes: I never really understood capacitors until I started trying to construct proper water-analogies for them. Then I discovered that my electronics and physics classes had sent me down a dead-end path with their garbage about "capacitors store electric charge." Since my discovery, I've gained significantly more expertise in circuit design, which leads me to a sad thought. Maybe the more skilled of…
Not really sure I like that link. He seems to suggest that capacitors store "energy" instead of charge, which is just as ambiguous really. It's not like there is some sort of energy particle either. Of course what's really happening is that you are creating an electric potential between two plates. It's true that the net charge is the same, but you are moving electrons from one plate and forcing them (doing work) into the other. Then when you remove the battery and have an open circuit, the potential remains because they have no way to move back to the other plate until you close the circuit again. Also, I don't think the water analogies work very well because water does not attract other water in any way, whereas in a capacitor, the electrons attraction to the electron holes in the opposing plate is an essential part of how a capacitor works and explains why the distance between the plates and the surface area are important.
Re: Why is electricity so hard to understand? (1989)
#50Earlier quoted context omitted.
From the linked notes: I never really understood capacitors until I started trying to construct proper water-analogies for them. Then I discovered that my electronics and physics classes had sent me down a dead-end path with their garbage about "capacitors store electric charge." Since my discovery, I've gained significantly more expertise in circuit design, which leads me to a sad thought. Maybe the more skilled of…
Not really sure I like that link. He seems to suggest that capacitors store "energy" instead of charge, which is just as ambiguous really. It's not like there is some sort of energy particle either. Of course what's really happening is that you are creating an electric potential between two plates. It's true that the net charge is the same, but you are moving electrons from one plate and forcing them (doing work) int…
I think you are missing the point of the water analogies. It is what made electricity make sense to me as well. But don't take it too literally, it's an analogy, not an identity.
If you start with things like "a motor is like a turbine, a generator is like a pump, a battery is like an elevated tank", a lot of things can fall into place. The point is you can visualize it.