potential difference

Discussion in 'Homework Help' started by GMChandio, Feb 26, 2015.

  1. GMChandio

    Thread Starter New Member

    Feb 26, 2015
    28
    0
    a battery of 6 volts is short circuited by a copper wire. What will be the potential difference across its terminals?
    ....
    According to me it should be 0, as the battery has short circuited so their should be no charge flow so it should be zero. But the answer is 4, HOW?
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    You're correct the answer is 0, but you're not correct in the reason why.

    An answer of 4 is wrong.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Was the internal resistance of the battery mentioned in the problem statement. Perhaps the 4 refers to 4A, which might be the short-circuit current.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    If can be 4V only if the resistance of the wire is twice that of the battery internal impedance.
     
  5. WBahn

    Moderator

    Mar 31, 2012
    17,757
    4,800
    So if you short out your car battery, do you REALLY expect there to be no charge flow?

    Always, always, ALWAYS ask if the answer makes sense!

    The answer most certainly is NOT equal to 4, if for no other reason than 4 is a number and not a voltage.

    Always, always, ALWAYS track your units!
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    In theory, a 6V battery cannot be 6V and 0V at the same time.

    In practice, you have to include real values.

    A short is never 0Ω
    The internal resistance of a real battery is never 0Ω.
    A real battery cannot supply infinite current.
     
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