Yesterday I saw a reference to Watt's law being used for the power formula P = V I.

It's been over 40 years since I learned my basic electrical engineering fundamentals and this is the first time that I recall seeing the phrase Watt's law used to represent this formula.

Doing some searching around on the web I haven't found where this term first showed up but have seen plenty of people on both sides of the flag claiming this is a proper law and others saying not.

Have done a fair bit of reading on Watt and his accomplishments in steam and mechanical power but don't recall that he ever did anything with electricity.

While the watt has since become a standardized unit of work (joules per second), I don't recall reading anything about Watt himself showing that volts times amperes equals power.

So, really interested in finding when/where this usage originated.

  • $\begingroup$ Interesting question. I recall my colledge teacher explaining me this formula but don't recall the actual explanation:). But it was a bit different with the intensity being the torque component and the voltage being the rotational speed. Anyway I'm also curious why joule/second did not replaced watt as the energy concept is younger than Watt's power concept acc to hsm.stackexchange.com/a/13309/19097 . Also j/s is more transparent and more intuitive. $\endgroup$ Oct 4, 2023 at 21:10
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    $\begingroup$ Does this answer your question? Where did $P=VI$ come from? $\endgroup$ Oct 4, 2023 at 21:14
  • $\begingroup$ The original question has been addressed. Stanford corrected their Wiki entry to remove the the confusing and erroneous text.Watt's. It had been made by a student who didn't fully understand the subject material and upon review Stanford made the fix. $\endgroup$
    – Daryl_71
    Oct 5, 2023 at 22:30


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