This blog is not an entry for the Proving Science challenge - but it does demonstrate Ohm's Law in action. Proving Science seems like the best place to put it.
E=IR In a different blog, I added extension cords to increase the resistance of a circuit and showed the resulting voltage drop across the extension cords. But that isn't the only way that the resistance of a circuit increases. What happens if we change the circuit resistance by decreasing the size of the conductor? Breaking strands happens in real life.
In the video demonstration, watch the voltage on the yellow multimeter to see the voltage difference across test bed as the equivalent conductor size gets smaller and smaller. Some interesting observations are that the circuit current does not change very much at all and the significant change in voltage across the test bed towards the end. It could even be exponential - as in like,.. I2, The voltage drop shows that even very small changes in the resistance of your supply lines can have an impact on the power the connected load receives.
I did this experiment a second time only with more time between wire cuts. There was no noticeable difference. I went a minute with only two strands. No change from the video. The electrical system stabilizes quickly. Blowing on the two strands was able to decrease the voltage drop by about 300mV, validating that temperature affects resistance. The next time I do this experiment, I'll use wire with courser strands - just to see if I can get that one last strand to glow but not open.
Top Comments
Very nice to have an auto ranging Fluke so you don't blow up your meter when the voltage jumps from mV to 119 V. This was a great illustrative addition to your entry.
John