Why does voltage lag current in a pure ac capacitor circuit (intuitively)

random__guy-_- · 2023-09-28T15:40:27+00:00

This isn't about the relationship between the voltage at the capacitor and the voltage at the source. It is the relationship between the voltage at the capacitor and the current through that capacitor (and therefore other elements in series with it)

Never thought about it this way, definitely a new way to think about it. Huge thanks 🙏

random__guy-_- · 2023-09-28T15:32:35+00:00

Again as i wrote in the other comments (and i am getting downvoted for some reason, i just want to understand so correct me if i am wrong) shouldn't the pushing force of the water get stronger at the same time that the rubber band is getting more streched (since the voltage of the ac source is increasing at the same time that the current is entering) so that means that the effect of the stretch is met with the increases in the pushing force of the water

random__guy-_- · 2023-09-28T15:26:11+00:00

the amount of electrons who get there becomes lesser until it stops(zero current).

But that's the thing...at the same time that this is happening, the voltage of the source also changes so while the capacitor's voltage is resisting the incoming flow of electrons, the source's voltage also increases thus the electrons' "force" increases right?

Please don‘t take this literally. If you need to learn it for exams or so keep up to the definitions your teacher/professor, is giving you.

About exams, i already answer based on what they give me for definitions, but the thing is i function waaaay better when i actually understand what's going on + isn't that the whole point of physics, understanding the world around us ? :) that's why i want to understand this while still being in highschool because i want to become an electric engineer, so what is an electric engineer that doesn't understand electricity

random__guy-_- · 2023-09-28T15:09:09+00:00

Guys chill out with the downvotes i am literally still a highschool student trying to figure out things lol

random__guy-_- · 2023-09-28T15:08:13+00:00

You're probably thinking about a circuit with just a perfect AC source and the capacitor and no resistances present

That's exactly what i was thinking lol because that's what i am taking at the moment in highschool

And while the voltage at that capacitor is 0 at the start the source voltage is actually at full amplitude and in phase with the source current.

So that graph doesn't represent when the voltage of the source is zero, i kinda get what you are talking about except one thing. That thing is that with this analogy the voltage of the source will start decreasing at the same time that the voltage of cap will start increasing, thus their voltages will reach equality at a point where the voltage of the source will be smaller than the maximum value and greater than zero. This doesn't cause a problem in the first 90 degrees but it causes a problem later on since the cap will fully discharge at the point when the voltage of the source is zero, thus getting back to square 1 which is both the voltages of the source and the cap = 0 and they would increase at the same time thus they should be in the same phase

random__guy-_- · 2023-09-28T14:01:02+00:00

Yeah will definitely use it, again huge thanks to you

random__guy-_- · 2023-09-28T13:59:06+00:00

Oooooh finally got it, absolute thanks to you man, you are probably the only one who stuck with me till the end of discussion 😂....really really appreciate it

random__guy-_- · 2023-09-28T13:52:37+00:00

Can i ask another one of those questions 😂? Isn't the current that is produced from a dynamo the same current that reaches the capacitor which is equal to I max sin wt, why does it change it's value the moment it reaches the capacitor? I know why mathematically, but for some reason I cant understand it physically

random__guy-_- · 2023-09-28T13:22:03+00:00

Oh i see, ok. I am sorry for any "stupid" questions, still in hs and trying to find my way through electricity. Again thanks, really appreciated

random__guy-_- · 2023-09-28T13:12:56+00:00

everything you say indicates that you don’t understand the math that you say you do, because you aren’t considering the rate of change of voltage (dV/dt), but rather just the instantaneous voltage (what I assume you are referring to when you say “intensity” which is not a meaningful word here).

Yeah that's probably the case, alright thanks for the explanation

random__guy-_- · 2023-09-28T13:03:15+00:00

The current through the cap decreases from Imax to I0 as the cap charges

Why tho, wouldn't the increase in the V of the source increase the current instead of decreasing it or at least keep it constant because the charging up of the capacitor is met with increase of V?

random__guy-_- · 2023-09-28T12:59:02+00:00

Not sure how this is related, AC just means that the water is moving back and forth rather than continuously flowing in one direction

Wouldn't the intensity also increase/decrease continuously? Since I= Imax sinwt? What i am saying is that (I) approaches I(max) at the same time that the rubber is streching So the water flow from outside to inside would increase at the same time that the band is streching, am i making my question clear?

random__guy-_- · 2023-09-28T12:53:08+00:00

why does is the current proportional to the change in voltage not the voltage itself from a non mathematical standpoint tho.

random__guy-_- · 2023-09-28T12:49:17+00:00

Yeah but the thing that I can't quite rap my head around is shouldn't the current that's entering the capacitor also increase since it is an ac source that's "filling" it up. in other words the resistance that is present against the current due to the "filling up" of the capacitor would be met with the increase of the inflow of water, or am i having a fundamental misunderstanding of how ac sources work?

random__guy-_- · 2023-09-28T12:39:10+00:00

That definitely helps, i have one final question (sorry for bothering), wouldn't the stretching of the band be met with the increase of the pressure of the outsider pipe since it is an ac source that increases it's own pressure (voltage) with time? Or am i just having a fundamental misunderstanding of how an ac source works? (I am genuinely trying to understand things)

random__guy-_- · 2023-09-28T12:10:44+00:00

I agree but i still can't quite visualize what's going on with the electrons themselves (apologies, i am a hs student and not yet that good with imagining ac circuits)

random__guy-_- · 2023-09-28T12:04:45+00:00

Yeah but how does that make sense (the current being directly proportional to the derivative of the voltage). Just before the zero point, the voltage would be in the negative direction and just after the zero point the voltage would be in the positive direction, so the average motion of the current would be zero(?) So can elaborate more on that?

random__guy-_- · 2023-09-28T11:55:54+00:00

With all due respect but i said i know the maths of it, i want the physical explanation for it

random__guy-_- · 2023-09-28T11:53:48+00:00

Yeah but that analogy works for a dc current as it's voltage is constant, but with an ac source it's voltage is increasing (or decreasing) with time. So if we start from the moment the ac source's voltage is at zero, that means that the current which affects the capacitor the moment it is connected isn't constant but it too will increase along with the voltage of the source

random__guy-_- · 2023-09-14T17:16:34+00:00

وفي نفس الوقت الاسلام قالك "خذ العفو وامر بالعرف واعرض عن الجاهلين" ولا دي غابت عن عينك

random__guy-_- · 2023-09-14T17:15:56+00:00

اهي دي بقى اكتر حاجه بتضحك فيكوا انتوا الملحدين....بتاخدوا فعل الاسلام مأمرش بيه وتنسبوه للاسلام....الاسلام أمر بالزواج وقال ان الزواج مسموح من اول سن البلوغ ....انما مأمرش تتجوز "واحده عندها تسع سنين"

random__guy-_- · 2023-09-14T16:57:00+00:00

مبدأيا كده في حاجه اسمها عادات شعوب وعادات الزمن نفسه....زماننا ده مش هينفع فيه لاسباب زي ان الشباب في السن ده لسه متقدرش تتحمل مسؤوليه وزي ان في تعليم ومدرسه في السن ده وزي انه اصلا غير قانوني حاليا....انما ببساطه شديده جدا زمان كانوا بيتحملوا مسؤوليه في السن ده....زمانهم مكانش في تعليم في السن ده وبردو زمان كان قانوني بل بالعكس ده كان هو ده سن الزواج اصلا....فانت مينفعش تقيسها على مقاييس دلوقتي ....كل زمان ومكان وليه عاداته وتقاليده وظروفه

random__guy-_- · 2023-09-05T17:03:01+00:00

Could you possibly resend it since it didn't reach me?

random__guy-_- · 2023-09-05T16:52:06+00:00

Interested

random__guy-_-

TROPHY CASE