/sci/ - Science & Math

when you pour water into your sink, how does it know which way the drain is?

>>11346286
Gravity

>>11346288
no, gravity compels it to go directly downwards

iq

It flows

>>11346282
Imagine you had a voltage between 2 points and in between those points was varying resistance. The arc will occur as soon as there is enough voltage to overcome the resistance and that will happen along the path of least resistance.

Wait till you learn that light takes the path of least time, that's going to really cook your noodle.

>>11346282
It's more like everything around it knows where it's supposed to go, thus funnels it there.

>>11346282

What is even electricity anyway, and how come it can cure homosexuality?

>>11346286
So do electrons initially take the easiest path even if down the line they find that path to be clogged? Then do they somehow make that resistance apparent for the electrons that haven't taken a path yet?

>>11346293
I've never seen a sink with an elevated drain

>>11346282
How does a river know the path of least resistance as it flows to the sea? How does a fracture in a piece of concrete know the path of least resistance? Nature just be like that.

>>11346332
How does a river know the path of least resistance as it flows to the sea? How does a fracture in a piece of concrete know the path of least resistance? How does a photon know the path through various media such that it minimizes the time it takes to reach its destination? Nature just be like that.

>>11346328
Look at slow motion lightning.

>>11346328
>that haven't taken a path yet?
i.e. further up the line

>>11346282
it doesn't. like charges repel and opposite charges attract, so charge flows.

>>11346282
>>11346286
It thinks really, really hard before it picks the path according to Ohm's Law and Kirchoff's Loop Rule

>>11346286
>counter question
>allegory
Fuck off

>>11346401
>allegory
It's not an allegory, though. An electron follows the path dictated by the gradient of voltage potential just as a water molecule follows the path dictated by gravitational potential. They are mathematically the same.

>>11346282
Imagine a T pipe filled with water and with one end closed. If you pour water into one end, why does it not pour out the closed end? Think on it and you'll find your answer

>>11346497
Does electricity back up or otherwise send a "signal" to electrons up the line in the same way?

>>11346282

Its got a TomTom GPS

>>11346503
No

>>11346525
Then either there is miscommunication on my part or that's where the water analogy actually breaks down.

>>11346544
No, the water analogy is pretty much right on. Image a tiny piece of water on some kind of surface in 3D space. That water will seek to minimize its potential energy, and it will always follow the path where the gradient of gravitational potential (aka, gravitational force) is maximized. This water has mass m.
Now, for an electron, we have the exact same situation. Just replace Fg=-grad(U) with E=-grad(V). They are identical.

https://www.youtube.com/watch?v=9NbCzbDdd-g
zero g

>>11346335
well, how do they?

Electricity takes all paths available — in inverse proportion to the impedance of the paths. The magnitude of the current flowing in a path depends on the path's voltage and impedance. The lower the impedance (assuming voltage remains constant), the greater the current. Conversely, the higher the impedance (assuming voltage remains constant), the lower the current.

>>11346282
EE master race here. It doesn’t. You are only thinking of something like lightning which is produced by a charge distribution. Once the voltage is high enough the electric field produced by the charge distribution is strong enough to ionize air and form a low resistance path to ground. A sharp spike in current flows and the charge distribution is dissipated so the lightning only lasts for a fraction of a second.

Electrons can still flow through non ionized air and they do. That is the point of a lightning rod. They attract charges and prevent the voltage from becoming high enough to cause lightning over that spot.

>>11346649
EE guy again. This guy is also correct. I should have added this in my answer

If lightning always follow the path of least resistance with doesn't it always hit France

>>11346692

>>11346571
The only thing that stops the water from going down the tube that is blocked off is the water gets backed up. You said this is not what happens with electricity. Therefore your fucking analogy is flawed.

>>11346731
>t. asks stupid shit like "does electricity get backed up?"

>>11346749
I was assuming the analogy isn't flawed. And that isn't stupid shit. Presumably the path can become "backed up" such that the previous electrons that tried to take that path now inhabit that path, hence backed up.

>>11346731
>>11346749
>>11346755

Electricity does get “backed up” though. If you connect a battery to a capacitor then current will flow initially. Once the charges on the capacitor form a voltage that is equal and opposite to the applied voltage from the battery then current stops flowing.

>>11346282
Pressure differential.

>>11346765
I'll break down the implicit question:
1. Does electricity initially try to take the path of least resistance only to find there is very much resistance further down the path?
2. If so, does the voltage change for the entire path analogous to water getting backed up?
3. If not, how then does the electricity "know" not to take the path in which, further along, there's an obstruction? Does the voltage somehow change instantaneously for the whole would-be path or...?

>>11346790
Gotcha. OP needs to take an intro to DC circuits course

>>11346790
>Does electricity initially try to take the path of least resistance only to find there is very much resistance further down the path?
No
>If not, how then does the electricity "know" not to take the path in which, further along, there's an obstruction? Does the voltage somehow change instantaneously for the whole would-be path or...?
At each point in the wire, there is a voltage gradient. The charge carriers (electrons) simply flow in this direction. It is that simple.

>>11346790
EE fag back again nigger

1. No, the total resistance of a path is all that matters for current flow. The exact distribution does not matter for resistance in series.

2. Of you know the voltage across a path, changing the resistance does not change the voltage, only the current.

3. Current flows in all paths available. It just flows greatest in the least resistance path

>>11346810
>It is that simple.
Then either I don't understand something simple, or you don't understand what you're talking about. It is far more likely it's the latter than that I'm stupid, as necessarily is someone who doesn't understand something simple. So this voltage gradient, does it instantaneously just exist at the beginning of the would-be path? Imagine a wire that is sufficiently long for you, say a mile. And the wire and an ideal path of least resistance are identical up until the last hundred feet, where there is a rubber stop has just, a picosecond, obstructed the path . Are you saying that the "voltage gradient" would reflect this fact and thus be different instantaneously for the entirety of the wire?

>>11346813
>It is that simple.
Then either I don't understand something simple, or you don't understand what you're talking about. It is far more likely it's the latter than that I'm stupid, as necessarily is someone who doesn't understand something simple. So this voltage gradient, does it instantaneously just exist at the beginning of the would-be path? Imagine a wire that is sufficiently long for you, say a mile. And the wire and an ideal path of least resistance are identical up until the last hundred feet, where there is a rubber stop has just, a picosecond, obstructed the path . Are you saying that the "voltage gradient" would reflect this fact and thus be different instantaneously for the entirety of the wire?
I'll include you as well >>11346829

>>11346790
>Does electricity initially try to take the path of least resistance only to find there is very much resistance further down the path?
No. Not all current flows down the path of least resistance, though.
>If not, how then does the electricity "know" not to take the path in which, further along, there's an obstruction? Does the voltage somehow change instantaneously for the whole would-be path or...?
At each point in the wire, there is something called resistivity. Resistivity is a property of the material itself. Resistance is something different. Resistance is defined as the product of resistivity of the material, times the length of the section of wire in question, over its correctional area. So R proportional to the length L of wire with resistivity ρ, and inversely prop. to its area A. Right? Now, it's an empirical fact that the current through a section of wire is proportional to the voltage over it, and inversely proportional to to R. I=V/R. This is Ohm's Law and that's just how it turns out that it works. If this doesn't satisfy you, go back to Maxwell's equations.
>okay but why
Not science. Ask God.

>>11346813 (Dead)
>It is that simple.
Then either I don't understand something simple, or you don't understand what you're talking about. It is far more likely it's the latter than that I'm stupid, as necessarily is someone who doesn't understand something simple. So this voltage gradient, does it instantaneously just exist at the beginning of the would-be path? Imagine a wire that is sufficiently long for you, say a mile. And the wire and an ideal path of least resistance are identical up until the last hundred feet, where there is a rubber stop has just, a picosecond ago, obstructed the path . Are you saying that the "voltage gradient" would reflect this fact and thus be different instantaneously for the entirety of the wire?
I'll include you as well >>11346829

>>11346846
>ask God
Based

>>11346847
The voltage gradient the physics guy speaks of is for voltage produced by electrostatic fields. Instead think of it like this: at the start of the wire you have a source of emf. This emf exerts forces on the electrons near the start, which further act on electrons in front of them. This is basically a wave that travels through the path at a very high speed, close to the speed of light. The high resistance at the end prevents the electrons at the end from traveling very fast, which in turn prevents electrons near the start from moving very fast. Ok?

>>11346847
>So this voltage gradient, does it instantaneously just exist at the beginning of the would-be path?
Yes. It exists absolutely everywhere in space all the time. This gradient is more commonly called "electric field" or E. Changes in E propagate at the speed of light and all of its properties and its relation to magnetism are described classically by something called Maxwell's equations, and described even better in special relativity. I deleted my post to give a clearer answer above. Look for the bunny.

>>11346859
That is the definition of voltage a physicist will give. They will call the “voltage” in a circuit electromotive force. Us electrical engies call energy per charge “voltage” regardless of the source because no matter the source the emf has the same effect for current flow.

>>11346847
I’ll also add that you are correct. It’s not simple at all. Developing a good intuition of how electricity behaves is not easy, especially from an EE point of view.

>>11346870
>That is the definition of voltage a physicist will give
They are equivalent definitions, just different ways of thinking about the same thing. Voltage being like the potential energy of each charge is a fine def. I'm an ME student, btw, so I'm flattered.

>>11346641
Due to all matter and energy ultimately being "composed of" massless particles at the fundamental level, the entire past present and future of the universe is actually "happening" at the same time, but in sequence, and instantaneously.

>>11347001
>this is the only way we can do the math, therefore it's true and that's how reality is
t. physicist

>>11347014
Are you actually contesting anything I said or are you just idly bitching?

>>11347017
>this is the only way we can do the math, therefore it's true and that's how reality is
Is a stupid way to think. How you like them apples? <-- not a real question

>>11347017
Not the same guy, but
>Due to all matter and energy ultimately being "composed of" massless particles
is straight up fucking wrong
>>11346641
principle of least (or stationary) action

>>11347022
>is straight up fucking wrong
Oh really

>>11347020
Idle bitching, then. At least >>11347022 is willing to say something other than "waaahhhh, I don't like the way you think"

>>11347062
>>11347057
shut up faggot. stop LARPing like you know any physics.

>>11347064
Do you?

>>11346995
Not necessarily. “Voltage” and emf both have the same effect in current flow for Ohm’s Law but the gradient of V is only defined for electrostatic fields. For instance, in magnetic induction the emf is produced by magnetic forces in a conductive loop, not an electric field. Either way I don’t think most physicists or EEs think about this sort of thing. But OP does bring up some good questions.

>>11346731
>You said
nah man it was me

>>11346282
It doesn't.

>>11347382
Based simple poster

>>11346286
nice

>>11346847
>Then either I don't understand something simple, or you don't understand what you're talking about. It is far more likely it's the latter than that I'm stupid
Yikes

>>11347532
>yikes
Besides the fact you are a faggot for saying yikes, he is correct. If you can’t answer his questions you are far dumber than he is

>>11347293
But anon, unless you forcibly shove an external magnetic field through the loop of wire that is an electrical circuit, you have it that the magnetic flux through the circuit is constant. If magnetic flux is constant, then the time derivative of it is zero. By Faraday's law, the line integral of E around the loop is zero. By Stoke's thm, curl(E)=0. It is a mathematical fact then that exists a function U such that F=-grad(U)=-grad(-qV) [this is the definition of V, and potential energy in general] and q is a constant. So all forces on a charge in the circuit are conservative and PE+KE is a conserved quantity and that if U and V the potentials for something conserved, then ΣV around a loop is 0.

So both definitions imply the other.

>>11347440
You are missed. Do you actually fuck off for a few or,do you just go incognito? ..., I noticed typos and didn't care. I'm cool like taht.

>>11346282

ECE here.

its simpler if you look at it in the atomic level. resistance is inherently a translation to the inability of an an atom to emit charge(more positive), when you put a source in a circuit, it creates a field which influences the conductors atoms. the electrons are moved in the circuit by being “pushed” by this field(aka your source), the electrons then flow from atom to atom, conductors are called such because these materials are made up pf atoms with much more free electrons that can “move”, now, the “direction” of where the electricity or electron flows depends on the electric field(your source), since opposite charges attract, electrons flow to the region where it is more positive, atoms that are receptors or those that have a “slot” for these electrons that flow producing electricity. essentially, electrons dont really know where they go, instead, they just flow according to the electric field, in this case, the battery from the positive to the negative terminal.

its much more complicated but i hope i explained this to you in a very simple way

>>11347070
Do you?

electric field

>>11347541
And if he isn’t understanding the answers then he is just a brainlet.

>>11348006
I sure think I do, but nobody has responded to my original point with anything except "that's wrong and I don't like it," with no comment on why they think its actually wrong

>>11348413
so you don't know any physics, got it.

>>11348425
no u

>>11347634
I have studied this subject quite a bit. A changing magnetic flux does not induce an electric field in the loop of wire. The emf is produced by magnetic forces on the charges. The way some physicists have accounted for this is by saying there is a virtual electric field induced in the loop, but I don’t think it really matters. There is also a practical difference in voltage from an electrostatic field and emf from another source. Electrostatic fields generally produce a high voltage that is not backed by much energy. Magnetic induction is capable of supplying far more energy over time than a charge distribution.

>>11346286
it keeps asking the turtles for the way down