# The relatively high resistivity of dry skin, about 1 \times 10^6

The relatively high resistivity of dry skin, about $1×{10}^{6}$ Ω • m, can safely limit the flow of current into deeper tissues of the body. Suppose an electrical worker places his palm on an instrument whose metal case is accidentally connected to a high voltage. The skin of the palm is about 1.5 mm thick. Estimate the area of skin on the worker’s palm that would contact a flat panel, then calculate the approximate resistance of the skin of the palm.
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William Appel
Consider the worker’s palm as a circle of radius 7cm. The area of the skin on the worker’s palm now becomes
$A=\pi {r}^{2}$
$=\pi {\left(0.07m\right)}^{2}$
$=0.0154{m}^{2}$
The resistance of the skin of the palm can be given by
$R=\frac{{\rho }_{sk\in }×t}{A}$
Substituting the values and solving gives
$R=\frac{1×{10}^{6}×1.5×{10}^{-3}m}{0.0154{m}^{2}}$
$=97441.8$
$\approx 97$