I was discussing about the theory that claims that "every emitter also behaves like a receptor": Are emitters always receptors? I was brilliantly told that this theory would be false for fluorescent lights and also for resistors, because of entropy messing with time-reversed operations (condensed version!).
However, as I'm curious by nature, I made this little experiment: heating a 330 Ohm resistor with a flame and measure its voltage with a cheap multimeter.
What a surprise to discover that some current flowed from this hot resistor!
At 20°C, I measured 0.0mV, after ±3 seconds of heating it was 0.6 mV (current around 1μA).
Have I just discovered some kind of "reversed" first Joule's law? :)
Or did I made some logical, methodological or experimental mistakes?