The resistance of a square centimeter of dry human epidermis is about 1.0x10 5 .

Question

The resistance of a square centimeter of dry human epidermis is about 1.0x105 . Suppose that a man firmly grasps two wires in his fists. The wires have a radius of 0.13 cm, and the skin of each hand is in full contact with the surface of the wire over a length of 8.0 cm.

a) Calculate the resistance the man offers to a currect flowing through his body from one wire to the other. In this calculation you can neglect the resistance of the internal tissues of the human body, because the body fluids are reasonably good conductors and their resistance is small compared with the skin resistance.

b) What currect will flow through the body of the man if the potential difference between the wires is 12 V?

Explanation / Answer

Part A)

The total surface area of the mans grip will be...

2 (2r) (L)

2 (2)(.13)(8)

Area = 13.1 cm2

We are given that the resistance is 1 X 105 per square cm

So total resistance is (1 X 105)(13.1) = 1.31 X 106

Part B)

Using Ohm's Law, V=IR

I = V/R

I = 12/1.31 X 106

I = 9.16 X 10-6 A   which is    9.16 A

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