Most of the resistance of the human body comes from the skin, as the interior of
ID: 1589207 • Letter: M
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. (a) What is the resistivity of the skin? (b) Compare your answer with the internal resistivity of the body, approximately 4.8 · m. (c) How do you explain the fact that the resistance of the skin is about 1000 times greater than the internal resistance of the body, even though the resistivity of the skin is only about 60 times that of the interior of the body?
1)Charges can only exist on the surface of conductors. 2)The resistance of an object scales exponentially with respect to the resistivity of the material out of which it is made. 3) The skin has a smaller cross sectional area. 4)The skin is constantly moistened by biological processes.
Explanation / Answer
resistance=resistivity*length/area
area=pi(radius with thickness^2-radius without thickness^2)=pi(7.2^2-7^2)=8.922 cm^2=8.922*10^(-4) m^2
length=1.6m
putting value
resistivity=278.8 ohm.m)
(b) It is much greater than the resistivity of internan organ
about 58 times greater
(c) the resistance of the skin is about 1000 times greater than the internal resistance of the body, even though the resistivity of the skin is only about 60 times that of the interior of the body?
because Charges can only exist on the surface of conductors
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