Suppose that each of a person\'s hands makes contact with a different conductor

Question

Suppose that each of a person's hands makes contact with a different conductor over a surface area of 10.5 cm2. We measure the hand-to-hand resistance of the body by connecting the conductors to an ohmmeter that reads 1.04 104 when the hands are dry. We know that internal body resistance is only about 600 .

(a) Find the resistance across a 10.5 cm2 section of the skin. (A= 4900 ohms) (b) Find the resistivity of the skin, assuming it is 1.01 mm thick. (c) Suppose the area of contact of each hand with a conductor is reduced to 1.08 cm2. Find the resistance between the hands.

Explanation / Answer

1.
R = Rb + 2Rs
Rs = (R-Rb)/2
Rs = (1.04 * 10^4 -600) /2
Rs = 4900

2.
= (Rs*A)/L
= (4900*10.5*10^-4) / (1.01 * 10^-3)
= 5094 -m
Resistivity, = 5094 -m

3.
Rs2 / Rs = A/A2
Rs2 = Rs*A/A2
Rs2 = 4900 * 10.5/1.08
Rs2 = 47639

R2 = Rb + 2*Rs2
R2 = 600 + 2*47639
R2 = 95878
Resistance between the hands, R2 = 95878 = 9.58 * 10^4

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