OF
Well-Known Member
i am suggesting that if this is the case, the temperature should continue to drop, not reach a stable point as it does (because, theoretically, the ends of the leads are outside the heated space). if such tiny leads could sink that much head, why are CPU coolers such big blocks of aluminum, for instance?
I think it would drop further if heat was not being conducted in at the same time. Like say if you pulled it out so conduction stopped?
I think this is demonstrated by Stu where we get two different 'signatures' in keeping with the lead diameter. Do you have a different explanation for why that happens? I think different heat flows lead to different drops and therefore different readings. The cup is still at one (higher) temperature. The drop is an instrumentation anomaly. It can be modeled.
Such tiny leads sink a small amount of heat for sure, but the replacement heat flow through the herb 'in still air' is very slow to get there so the local temperature drops. Notice in Stu's test that fatter leads showed a bigger effect, both in absolute temperature being lower (thin leads read higher since they sink less heat) and the step size. I think if we could use even thinner leads they would be yet closer to 'flat line'?
Between hits why else do the two different gauges of leads show different temperatures?
Heatsinks that have to move lots of power (Watts or calories, take your pick) need fat paths with low resistance (the reason for big size) and rapid transit to the air (which is why fans are added) to do that job. Remember the 'degrees C per Watt' deal I talked about above? That is why. We also add 'goose grease' to improve the heat flow between device and heatsink for the same reasons.
Tough stuff, counter intuitive from some perspectives for sure.
Regards to all.
OF
Edit: Here's another anology if you've the patients for it? Ever notice how the kitchen light dim when the washer starts? Or a vacuum or other high current load. The voltage drop is from the increased current flow, the voltage 'at the poles' doesn't sag. Or you can see your car light dim when the battery has to provide more current to crank the engine? Same deal as we're looking at here basically.
OF