I would like to ask a simple question :How are proportional relationships in physics found?
To be more specific, let's consider a simple law, Ohm's law, which states $\Delta V\propto I$. Now, it seems intuitive that as the potential difference increases, the current must also increase. But it doesn't seem intuitive at all that it would increase by the same factor. So, how are laws like these established? Is it just empirical or is there a theoretical way to do this?
NOTE: I am considering that proportionality means the same in physics, i.e if $a \propto c$, then $a/c = constant$.