Most of the resistance of the human body comes from the skin, as the interior of

Question

Most of the resistance of the human body comes from the skin, as the interior of the body contains aqueous solutions that are good electrical conductors. For dry skin, the resistance between a person’s hands is measured at typically 500 k. The skin varies in thickness, but on the average it is about 2.0 mm thick. We can model the body between the hands as a cylinder 1.6 m long and 14 cm in diameter with the skin wrapped around it.

1) What is the resistivity of the skin? (Express your answer to two significant figures.)

Explanation / Answer

length=1.6 m

inner radius of the cylinder=diameter/2=7 cm

outer radius=7 cm+thick ness of the skin=7 cm+2 mm=0.07 m+0.002 m=0.072 m

cross section area=pi*(outer radius^2-inner radius^2)

=pi*(0.072^2-0.07^2)=8.9221e-004 m^2

then resistance=resistivity*length/area

==>resistivity=resistance*area/length

=500*10^3*8.9221*10^(-4)/1.6=278.82 ohm.m

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