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Physics/Power and electricty


Hi Dr.Nelson, I had a question regarding the power equation that uses electricity. I read that P=i^2R tells you power lost during transmission, so does P=iV tell you power generated? (which is technically the same because the power generated would equal to the power lost from the source)and if true, then where does P=V^2/R fit into all this? Does it tell us power lost or generated?

They're all the same equation, since according to Ohm's law V=IR.  Most materials are Ohmic in nature.  So it's just algebraic substitution.  If you re-write your first equation as P=I^2R=I(IR) and use V=IR then you get P=IV.  You can keep doing that kind of re-writing and get all three power equations.  They're all the same.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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