A question regarding terminals of battery

Discussion in 'General Electronics Chat' started by Vorador, Jan 17, 2013.

  1. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Hello everyone,

    I have an embarrassing question. I wanted to ask that, if I just connect one end of a resistor to the positive terminal of a battery, would that terminal of battery strip off the electrons from the resistor and lose its positive charge?

    I'm sure that's not what would happen, but I can't realize why because I've never understood batteries very well.

    Thank you very much!
     
  2. mrmount

    Active Member

    Dec 5, 2007
    59
    7
    There will be no movement of electrons in that case. Electrons start moving only when the loop is closed.
     
  3. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Yeah, but that's when you want a sustained current, right?
    Two oppositely charged particles must attract by electrostatic force, loop or not?
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Does the battery loose it's charge if you touch one of it's terminals? No, despite your skin having a electrical resistance.

    Forget about attracting forces in the example you gave.

    Whenever you have a voltage from a power supply, be it DC or AC, be it a battery or grid voltage or a solar cell there will only be current when you provide a path for this current to flow.

    If you touch the battery terminal with a resistor and leave the other terminal disconnected there will be no current flow.

    Current can flow through air if it is ionized but that is not what you asked right? :)
     
  5. bretm

    Member

    Feb 6, 2012
    152
    24
    Technically true but the effect would be immeasurably small. There are so many free electrons that they would only need to shift position by a fraction of an atomic diameter to restore equilibrium.
     
  6. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    @praondevou: Yeah, as I said, I'm sure that's not what happens but I don't understand why. I'm not finding it easy to just "forget" about one of the most fundamental laws of nature lol.

    Thanks for your help guys! :)
     
  7. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Oh. I'm glad I wasn't absolutely wrong about this one.

    Could you kindly please explain how the equilibrium would be restored in just a little more detail? I'd really appreciate it very much!

    Thank you so much for your response everyone! Please bear with my ignorance.
     
  8. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    It could also flow if you exceed the dielectric strength...but that requires a BIG battery :)
     
  9. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    You can look at it as a capacitor with a very small stray capacitance between the resistor and the negative battery terminal. In a capacitor, charge is moved according the equation Q = CV where Q is the charge in coulombs (1 coulomb = 6.24150965× 10^{18} electrons), C is the capacitance and V is the voltage difference. Since the stray capacitance is very small (essential a short wire in air, likely much less than a picofarad) the amount of electrons moved is also relatively small as compared to the total number of electrons in the wire.
     
    Vorador likes this.
  10. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Ookay, I understand that. Thank you very much! :)

    So, would the resistor find itself lacking an electron or two?
     
  11. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    Yes. Likely more than one or two. ;) The number of electrons can be calculated by the formula in my previous post, if you determine the value of the stray capacitance.
     
    Vorador likes this.
  12. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Thank you so much sir and everyone else who responded to this thread. You've been a great help! I really appreciate it! :)

    Is there any chance that I can use such a resistor to make my hair stand on end due to electrostatic forces? :D
     
  13. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    Only if the resistor is attached to several tens of thousands of volts. :rolleyes:
     
  14. Vorador

    Thread Starter Member

    Oct 5, 2012
    87
    1
    Oh hehe. Silly me.
     
Loading...