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Question:
Recently I used a multimeter to test resistance between the left and right hand of student. It came out to be about 200 k . Using ohm's law I found that current drawn from a 120 V socket would be about 0.0006 A, hardly noticeable. Yet I know that more current than that would be drawn. What am I not taking into account?


Replies:
Well, I just checked my own, and it is even higher! Yet, I am not going to stick my fingers in the socket. The surface area of contact is important (multimeter probes provide a pretty small contact area), but even more important is the amount of moisture on the skin's surface. Try it with sweaty hands, and you will see at least an order of magnitude reduction...now we are talking about 6 millimps (milliamps), which is noticeable and is of the same order of magnitude as potentially fatal shocks. I also recall that as soon as a small amount of current is passed, the resistance of the skin drops rapidly...do not remember why. If you want to pursue this, get back to me and I will check with our electrical safety engineer for details. --Gary

gary e myers


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