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#1
07-02-2011, 04:50 PM
 phill.oye New Member Join Date: Jul 2011 Posts: 2
P=IE?

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
07-02-2011, 05:07 PM
 someonesdad Senior Member Join Date: Jul 2009 Location: Northwest USA Posts: 1,584

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.
 The Following User Says Thank You to someonesdad For This Useful Post: phill.oye (07-02-2011)
#3
07-02-2011, 05:09 PM
 blah2222 Senior Member Join Date: May 2010 Location: West Posts: 506

Quote:
 Originally Posted by phill.oye 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.
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)
 The Following User Says Thank You to blah2222 For This Useful Post: phill.oye (07-02-2011)
#4
07-02-2011, 07:33 PM
 phill.oye New Member Join Date: Jul 2011 Posts: 2
cheers

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
07-02-2011, 08:28 PM
 someonesdad Senior Member Join Date: Jul 2009 Location: Northwest USA Posts: 1,584

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.
 The Following User Says Thank You to someonesdad For This Useful Post: phill.oye (07-02-2011)

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