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Electrical Energy Transferred

  1. Jun 28, 2013 #1
    Can anyone tell me how to calculate electrical energy transferred when you are given a voltage and a charge? I'm really stuck as we haven't covered this before :-/
     
  2. jcsd
  3. Jun 28, 2013 #2

    CWatters

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    Hopefully you recognise...

    Power = Voltage * Current
    and
    Energy = Power * Time

    So

    Energy = Voltage * Current * Time

    but

    Current * Time = Charge

    (Edit: or if you prefer Current = Charge/Time)

    So

    Energy = Voltage * Charge
     
  4. Jun 28, 2013 #3
    Ok, yeah I got as far as Energy = Voltage * current * time, but I'm afraid I don't understand how you got to energy = charge * voltage? (Probably being extremely dumb here...)
     
  5. Jun 28, 2013 #4

    CWatters

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    Ok so you got as far as ....

    Energy = Voltage * Current * Time .......................... (eqn 1)

    Think about what current is. Current is the amount of charge flowing past a point per second. Just like the current of a river is the amount of water flowing past per second.

    So the definition of current is Charge/Time

    Now in equation 1 above you can replace "Current" with "Charge/Time" to give

    Energy = Voltage * (Charge/Time) * Time

    Time cancels to leave

    Energy = Voltage * Charge
     
  6. Jun 28, 2013 #5
    Oooh I understand now! Thank you very much!!
     
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