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Voltage reference point

  1. Jul 17, 2012 #1
    Hello

    I know that 5 volts in reference to ground (0 volts) is 5 volts as there is a potential differencce of 5 volts between 0 and 5 volts.

    Does this mean 5 volts in reference to 2 volts would be 7 volts as there is a potential difference of 5 volts between 2 and 7 volts?

    Thank you for any replies
     
  2. jcsd
  3. Jul 17, 2012 #2

    mfb

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    What are "5 volts in reference to 2 volts"?
    If you connect the "-"-side of a 5 volt power supply to a cable which has +2V (with your definition), the "+"-side will have +7V.
     
  4. Jul 17, 2012 #3

    phinds

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    If you are talking apples to apples (same ground reference in the same circuit) then 5 volts is 3 volts above 2 volts.

    Your argument is exactly like saying that if I have 5 apples and you take away 2 of them, I should now have 7 because there is a difference of 5 between 2 and 7.
     
  5. Jul 17, 2012 #4

    CWatters

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    Voltage difference = Voltage on point A - Voltage on point B

    Examples

    Va Vb Difference
    5 0 5
    5 2 3
    5 -2 7
    -5 -3 -2
     
  6. Jul 17, 2012 #5
    potential diff is exactly that, -5 to -10

    potential being the power-of-the-universe/desire to go from one difference (ie ground state) to another

    difference.. being the "key word" in "potential difference" : excludes the ground/zero state

    (as the ability of voltage/potential difference to perform is the same)
     
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