Electricity tends to flow through the path of least resistance

Hi David,

The answer to this is simple. Electricity tends to flow through the path of least resistance.

So, if you are zapping a body of water with 4 corners, the electricity goes almost directly from one electrode to another. Very little reaches the other corners.

Similarily, in a human, if you are holding one electrode in each hand, the electricity will flow out of one electrode, up that arm, straight across the top of the chest, down the other arm, and out the return electrode. It does not travel down the torso towards the legs.

If you wanted to have the signal penetrate the torso, you would need for it to travel up the legs, up through the torso, and out the arm with the return electrode.

See pictures at http://paradevices.com/how_to_zap.html

As for why one negative ( return ) electrode? If you observe motile microbes being zapped, you will generally notice that the microbes tend to migrate towards the negative and away from the positive. Also, the microbes nearest the positive electrode die first and the ones nearest the negative live the longest.