P=IE?

Discussion in 'Feedback and Suggestions' started by phill.oye, Jul 2, 2011.

  1. phill.oye

    phill.oye Thread Starter New Member

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    Hi, I'm just wondering if the formula P=IE is correct in following definition under DIODE RATING: "given the dissipation (P=IE) of diode current multiplied by diode voltage drop".
    I know that U=∫Edl, but haven't seen written P=IE and from the sentence above the lette "E" is decribed as voltage drop.
  2. someonesdad

    someonesdad Senior Member

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    Yes, it's a common abbreviation for voltage, coming from "electromotive force". Physicists typically don't use it because it can be confused with the electric field symbol.

    Personally, I feel a site should standardize its notation and V is used for voltage more than E, so I think your observation's a good one.
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  3. blah2222

    blah2222 Active Member

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    Yes, that is true. The voltage drop of the diode multiplied by the current passing through the diode is the power dissipated.

    The Integrated equation that you have there is having U being voltage, and it is not really used for circuit analysis because we never really consider distances or electric fields, unless you are into professional design or something.

    So basically:

    Power Dissipated = Voltage Drop * Current

    Voltage = Integral(Electric Field (dot) Incremental Length)
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  4. phill.oye

    phill.oye Thread Starter New Member

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    Ok then. Thanks for explanation. As I found a voltage may represent a source of energy (electromotive force), or it may represent lost or stored energy (potential drop). So does it mean that in our case it represent the electromotive source or just the voltage is sometimes defined as "E" and sometimes as "V"?
    Sorry for my equation with "U" as a voltage. The symbols differs from country to county, but how come that a voltage is not standardized internationally only to one symbol "V"? Or, is it?
    Cheers
  5. someonesdad

    someonesdad Senior Member

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    An author is free to choose whatever symbol they want for potential and there is no standardization. At best you can say that E and V are two customary symbols for potential, but so are many others, such as v, phi, and mu. That's why it's important to define your terms; many people don't and don't realize that a symbol can mean many things to many people. Thus, eliminate confusion by defining your symbols.
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