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Potentiometer Fire, Smoke and Sparks

Easy. Gimme a guitar, a car battery and a set of jumper cables. :D

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I don't know what the voltage is under the load, but it's safe to call the maximum VPeak​*IPeak​, for this rough estimate of Power.

Sure it is safe, there is no way the number you get can hurt you in any way. And, if you multiply any voltage by any current the number you get will have the units of Watts. But if you want to claim the number represents the amount of power the battery can supply to a load the voltage and current have to be measured under the same conditions. Making them at the same time guarantees that will be true.

Your peak voltage*peak current is 8.9*4.9 = 44W. A reasonable assumption is that the Ammeter resistance is near zero and that 8.9/4.9 = 1.8Ohm is the battery internal resistance when you first connect the meter. The maximum load power will occur when the load equals the internal resistance. Under those conditions the total power would be 8.9*8.9/3.6 = 22W and only half that, 11W, will appear in the external load, the rest will be dissipated as heat in the battery. It is clearly enough to smoke a pot but not nearly 44W.

Ken
 
Even I am not sure I believe it. The only reason I DO remember it was, the guy bought some mic cables from us and a batch we had in stock all had pin 1 connected to the shell on BOTH ends, and we thought either we'd be sued or else someone would get killed.
 

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