1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

AC flowing through a cap. What actually happens?

Discussion in 'General Electronics Chat' started by qtommer, Feb 25, 2011.

  1. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    MrAl,

    No, I disagree. If the energizing of a battery is "acknowledged with a successful accomplishment", then it can be taken to mean that the battery now performs to specifications.

    Ratch
     
  2. MrAl

    MrAl Well-Known Member Most Helpful Member

    Joined:
    Sep 7, 2008
    Messages:
    11,032
    Likes:
    952
    Location:
    NJ

    Ratch,

    Well, that's not true at all because it's still the same story:

    When we say *energize* and we say 'it did energize' we could mean that "it energized but it didnt store energy".
    When we say *charge* and we say 'it did charge' we can only mean that it took a charge.

    We dont have to say anything else about the battery when we say 'charge', yet we do have to specify 'if it held energy' if we use the word 'energize'.

    Note also that when we say we 'charge' a battery that also doesnt mean that we dont know yet if it charged successfully or not (same as energize) but when we say it was successful then only 'charge' adequately describes what took place.
    We dont have to add any additional qualifying information when we say 'successfully charged' but when we say 'successfully energized' we have to add additional information.

    When we say 'battery' that in itself does not say that the battery is good or not, but when we say 'successfully charged' we know it was good. When we say 'successfully energized' we dont know if the battery was good or not.

    In other words, there are two ways to successfully energize a battery while there is only one way to successfully charge it.
     
  3. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    MrAl,

    No, I disagree. I take energize to mean a completed successful process, not an attempted action, and not just turning on the reverse current. Failure is not an option.

    Ratch
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. tvtech

    tvtech Well-Known Member Most Helpful Member

    Joined:
    Mar 27, 2010
    Messages:
    3,166
    Likes:
    348
    Location:
    South Africa

    Original posters question:

    AC flowing through a cap. What actually happens?

    "We all know DC gets blocked and AC passed when going through a capacitor. Assuming an AC signal propagating through a cap, can anyone explain specifically the flow of electrons acting on the capacitor which hence allows the signal to be passed through? just curious all this while. Couldn't find any book/site which specifically explains why this happens."

    The answer to the question was already posted and explained on the first page.

    Why this complicated discussion which is now about batteries??

    The OP has left ETO for ever.

    No one ever agrees with Ratchit. He is simply here to stir.

    And the knowledgeable regulars here fall for it all the time.

    Ti's true.

    Cheers





    Thanks=)
     
  6. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    tvtech,

    Because we are on a different topic now.

    How do you know? He got his question answered, didn't he?

    False statement.

    No one falls for anything. No one has to read this thread. No one has to believe this thread. We each express our own viewpoint. Everyone decides what to believe.

    And do you believe it?

    Ratch
     
  7. MrAl

    MrAl Well-Known Member Most Helpful Member

    Joined:
    Sep 7, 2008
    Messages:
    11,032
    Likes:
    952
    Location:
    NJ
    Hi again,

    Well that is just how *you* take it then. The *act* of trying to do something does not always mean that it was successfully done.
    When you charge or energize something you are performing an act, not guaranteeing an outcome. It's true that sometimes you do, but not when the word used to describe the act can mean either outcome. "I applied the force to the object", did it move or not? "I moved the object", we know what happened without asking.

    The act of giving energy to means to apply energy. It says nothing about how the object uses that energy.
    The act of charging means to apply energy. It implies something but strictly speaking also may not describe how the object reacts.
    We can say that there may be little difference there, but...

    The act of successful energization means a successful *application* of energy without specifying if it was also a successful *acceptance* of energy as storage.
    The act of successful charging means a successful application of energy with also the successful acceptance of energy.

    Thus charge can say something more to the point than energize.

    Remember the whole point here is to be able to describe the act of successfully charging a battery (or successfully supplying energy to a battery and having it stored).

    With energize, in both cases i was able to successfully supply energy, but only one case stored it.
    With charge, there's only one successful case and that's where the battery stored the energy.

    Thus 'charge' is less ambiguous.

    You cant argue both ways, either energize means to apply energy and have it stored, or as with a resistance have it dissipated. Since you agree that you can energize a resistor or a battery, then you cant argue that we have to always use a brand new battery just to be able to energize it! That's totally off the wall :)


    tvtech:
    Yes ok we'll have to stop soon. It's been interesting though :)
     
    Last edited: Mar 2, 2011
  8. tvtech

    tvtech Well-Known Member Most Helpful Member

    Joined:
    Mar 27, 2010
    Messages:
    3,166
    Likes:
    348
    Location:
    South Africa
    All I can say is Thank God I don't work with, play with, or discuss anything with someone like you.

    I would be crazy within the first few minutes.

    @Ratch...if I gave you a peg to hang washing up....would you take the plastic one or the original wooden one?

    It would probably need discussion:

    1. Wood is older than plastic.
    2. Wooden pegs have a reliability record of note.
    3. Plastic is lighter though.
    4. Plastic pegs are cheaper.

    And so on.

    The washing is still waiting to be dried though. And not hung up to dry.

    Cheers
     
    Last edited: Mar 2, 2011
  9. Ressie

    Ressie New Member

    Joined:
    Mar 2, 2011
    Messages:
    2
    Likes:
    0
    I had to register for this, as I came across this forum post out of pure curiousity. I already know how a capacitor functions, in both respsects to AC and DC. I just thought it very interesting to see how others would explain it though, and had understood the explanations without need for any reference, albeit for the post by Ratchit. After going through 10+ pages of replies, I can only say that as an academist, I was taken aback at the overly intentional complexity put into Ratchit's replies. It's obvious by the amount of trolling responses made, that their responses are aimed at the expense of the reader. A little Occam's razor goes a long way. If someones asks for an explanation, one need not have to pull out an encyclopedia, or in this case a principles of electronics book, in order to decipher the answer. Brevity and succintness seems to be lost to them. Arguing over the colloquial usages of terms is also base, and I find it irritating to have to read over Ratchits insistence that they are correct on all accounts, as if the whole world adopts their viewpoint.

    I apologise if this seems a bit like flame-baiting, but I wholeheartedly believe the inclusion of their posts detracts from the initial OP's question, and the follow up responses.

    Everyone continue with the great posts, and I hope to see more informative threads on this site as I visit in the future.
     
  10. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    MrAl,

    I take the word we are discussing to mean success, not the act. If you want to mention the action, then you should say "energizing".

    A little difference with respect to what? How the object uses the energy is irrelevant.

    I just don't see it that way. If you want to denote successful completion, then say "energize". If you want to denote an attempt, but an indefinite outcome, then say "energizing".

    Use "charge" or "charging" depending on what you want to convey.

    Not fair to compare the two. A resistor is supposed to dissipate power when energized. A battery is not. I don't get the part of always using a brand new battery.

    Ratch
     
  11. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    tvtech,

    You had better get busy then.

    Ratch
     
  12. tvtech

    tvtech Well-Known Member Most Helpful Member

    Joined:
    Mar 27, 2010
    Messages:
    3,166
    Likes:
    348
    Location:
    South Africa
    Thank you for your to the point post and welcome to ETO.

    Cheers
    TV Tech
     
    Last edited: Mar 2, 2011
  13. BrownOut

    BrownOut Banned

    Joined:
    Jun 10, 2009
    Messages:
    4,630
    Likes:
    60
    Location:
    Huntsville, Alabama USA
    Welcome Ressie, sorry you had to come in on such ostentatious exhibit by one of our members. All of us are pretty much irritated with these types of threads. We do have some half decent discussions from time to time, however.
     
  14. Mr RB

    Mr RB Well-Known Member

    Joined:
    Jul 22, 2008
    Messages:
    4,716
    Likes:
    194
    Location:
    Out there
    Just bite the bullet Ratchit you are wrong.

    You can't tell a bunch of long-term experienced experts in a field that they must all stop using the standardised and required terminology of the field and start using the special words you like best. It's an idiotic attitude, marking you as either an idiot or a trouble making troll.

    Secondly you neatly avoided my debunk of your "no current flow through a capacitor" bunkum with my example of a capacitor being one component in a series circuit with all components and ammeters showing a measured and quantified current flow. What happens inside the capacitor is irrelevant, a theoretical capacitor (that has no chemical, physical or mystical process within it) has a current flow that is clearly understood when in an AC series circuit.

    That's two areas you have blown badly... And you can probably add a third mistake of annoying a lot of experts. It's not looking good for you. Time to go cause trouble somewhere else dude.
     
  15. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    MrRB,

    I don't think so.

    I never said they "had" to do so. I was pointing out a better way to describe something.

    I believe I said that just because current can be measured on both sides of the capacitor was not proof that charge passes through the capacitor. If it did, the charge would not accumulate and it would not do what a capacitor does, store energy. Why didn't you discuss this earlier?

    I don't agree with your propositions.

    Ratch
     
  16. ljcox

    ljcox Well-Known Member

    Joined:
    Dec 25, 2003
    Messages:
    3,205
    Likes:
    28
    Location:
    Melbourne Australia
    You don't understand displacement current.
     
  17. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    ljcox,

    How so?

    Ratch
     
  18. MrAl

    MrAl Well-Known Member Most Helpful Member

    Joined:
    Sep 7, 2008
    Messages:
    11,032
    Likes:
    952
    Location:
    NJ
    Yes i know how you take it, but that's not how the rest of the world takes it :)

    Are you kidding me? I guess you wont mind supplying my home with electrical energy for the next ten years then since it doesnt matter how i use it. Store it and give it back, or just burn it up in light bulbs :)
    Of course it is relevant. We would like to know if the battery stored the energy so we can start our car in the morning or just ate it up so we know enough to buy a new battery.

    Wait a minute, after all this discussion now you are telling *me* to use the word 'charge'?




    Yes that's correct, but what an element is supposed to do is not always what it does. Surely you can understand that? A brand new battery means you wont allow a defective battery into the circuit just because you want to use the word 'energize'. If you would just use the word 'charge' then you wouldnt have to worry about the state of the battery beforehand.

    I think you need to change your sig line because you are not being pedantic, you're being ignorant. Im not saying that you are stupid either by any stretch of the word so dont misinterpret that too, im just saying that you are ignoring the facts and substituting opinions, that's all.

    If you are not convinced then go about and see how many people think 'energize' is an appropriate description of the act of charging a battery. Tell them you energized your battery and see what they say in reply. Many of them will not know if you are charging the battery or discharging the battery.
     
    Last edited: Mar 2, 2011
  19. MrAl

    MrAl Well-Known Member Most Helpful Member

    Joined:
    Sep 7, 2008
    Messages:
    11,032
    Likes:
    952
    Location:
    NJ

    Hi there and welcome to the forum,


    When the discussion first started we thought we would supply some useful information to Ratchit and that he would be happy to be able to obtain and use that information. It turned out that it took much longer than expected as you can see. He had some useful input to the thread if you read way back when, but then i think he may have gotten off on a tangent and was bent on proving that 'energize' is the same word as 'charge' (or a similar argument).

    In any case, we often talk about interesting things on this forum and only once in a while have these kinds of disagreements so this thread is the exception to the rule by far. One bad thread out of thousands of good ones isnt really that bad after all.

    And with that last note i think i'll bow out of the thread too now and move on to some other topics, as i am sure i made the point i wanted to make and if it doesnt get through well then i know i have at least put the effort forth in order to try.
     
    Last edited: Mar 2, 2011
  20. ljcox

    ljcox Well-Known Member

    Joined:
    Dec 25, 2003
    Messages:
    3,205
    Likes:
    28
    Location:
    Melbourne Australia
    Ratchit.
    You seem to think that there must be molecules in the space betteen the plates. But as I said, it can be free space, ie. a vacuum with NO particles in it.

    See
    Displacement current - Wikipedia, the free encyclopedia

    Here is the relevant section.

    Generalizing Ampère's circuital law
    Current in capacitors
    An example illustrating the need for the displacement current arises in connection with capacitors with no medium between the plates (in free space). Consider the charging capacitor in the figure.

    The capacitor is in a circuit that transfers charge (on a wire external to the capacitor) from the left plate to the right plate, charging the capacitor and increasing the electric field between its plates.

    The same current enters the right plate (say I ) as leaves the left plate.

    Although current is flowing through the capacitor, no actual charge is transported through the vacuum between its plates.

    Nonetheless, a magnetic field exists between the plates as though a current were present there as well.

    The explanation is that a displacement current ID flows in the vacuum, and this current produces the magnetic field in the region between the plates according to Ampère's law.

    Free space
    Vacuum - Wikipedia, the free encyclopedia
     
    Last edited: Mar 2, 2011
  21. Ratchit

    Ratchit Well-Known Member

    Joined:
    Mar 12, 2008
    Messages:
    1,935
    Likes:
    78
    MrAl,

    I will be happy to explain.

    I guess you would know that if the battery was energized or not.

    I don't understand what you mean. Just using different words is no substitute for testing the battery afterwards.

    Substituting opinions, yes. Ignoring the facts, no.

    Yes, I will. However, I don't get a change to do that activity very much. I'll keep it in mind, however.

    Ratch
     

Share This Page