I am not someone specialized on physics, I am just curious on why our Body Electrical Resistance measure as shown by a multimeter varies so much. When allocating the 2 probes each on one hand, the resistance varies from low 100k's of Ohms up to 700k Ohms and even more. Can someone illustrate in a easy way for a physics dummy this phenomena? Thanks
The bodies internal electrical resistance is quite low. Bodily fluids have enough ions (dissolved salts mainly) for the conductance to be high. The thin layer of skin provides almost all of the resistance. Once the skin resistance is overcome (by wetting, or for higher voltages arcing), the low internal resistance dominates. So for instance, how good a contact is made, how much surface area, and whether conductive jelly is used makes a large difference. Lie detectors use skin resistance, which largely measures sweating, as one among several measures to try to ascertain the emotional response of the subject.