= Passive sign convention
{title2=$p_{\rm absorbed}=VI$}
The <passive sign convention> defines terminal <electric potential difference> $V=\phi(A)-\phi(B)$ and positive <electric current> entering at $A$. Then $VI$ is absorbed electrical <power>: positive means the component receives <energy>, negative means it supplies <energy>. Reversing both reference directions leaves the product unchanged. For a positive <electrical resistance> obeying <Ohm's law>, both $V$ and $I$ reverse together and <Joule heating> remains $I^2R\geq0$.
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