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Homework Help: Work done of charger of a battery

  1. May 1, 2014 #1
    NEVER MIND! I realized my question is kind of stupid. Its night here and I am kind of sleepy. :))

    1. The problem statement, all variables and given/known data
    a battery of 4V is connected opposite to a battery of 2V to charge the 2V battery. assume the current running through the circuit to be 2 Ampere. What is the Work done by
    1) the Whole circuit
    2) By the 4V battery
    3) by the 2V battery

    2. Relevant equations
    Work = Voltage x Charge

    3. The attempt at a solution
    1) I know that 2 A is 2 Columb/second. and since the two batteries are opposite the whole circuit work done is (4 - 2)V x 2 Columb = 4 J
    2) for part 2 and 3 I am not sure I I should consider each battery by its own or what to do?
    Also if we do do consider both, Isn't the current flowing in the 2V in the opposite direction of its positive terminal therefore makes it negative Work done!! (work done is scalar)
    a little clarification and a little help with the question would be really appreciated :))
    Last edited: May 1, 2014
  2. jcsd
  3. May 1, 2014 #2


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    2017 Award

    Voltage x Charge doesn't give you the correct dimension. Voltage x Charge/time does. Charge/time is also known as current.
    [edit] Oops :redface:, my mistake. Tooooo quick. Work is what you want, not power.
    [edit2] Is this really the full text of the exercise ?
    [edit3] Night here too; only now do I read the very first line... Oh well, :smile:
    Last edited: May 1, 2014
  4. May 2, 2014 #3
    Hahahahaha No problem man :D :D Sleepiness does more :)) :D
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