Originally Posted by
Jerome Hanby
Not that this really matters, but that's the Basic Power Formula, sometimes (incorrectly) called Watt's Law. The watt was named in honor of James Watt, but he had nothing to do with calculating electrical power. He did coin the term Horsepower, which is often associated with power expressed as watts, so it's not completely off the mark to honor him. Ohm's Law is useful for redefining elements of the Basic Power formula to make it more useful, for instance voltage could be expressed as I * R, which would make power equal to I^2 * R
The Basic Power Formula is actually a combination of Joule's first law (which described heat generated by current flowing through a resistor over time) and Ohm's law. Just fyi Joule's first law:
Q = I^2 * R * t
Which using Ohm's law could convert to:
Q = V * I * t
Pretty close to the Basic Power Formula...