Question

The average resistivity of the human body (apart from surface resistance of the skin) is about 5.0 Ωm. The conducting path between the right and left hands can be approximated as cylinder 1.6 m long and 0.10 m in diameter. The skin resistance can be made negligible by soaking the hands in salt water.
(a) What is the resistance between the hands if the skin resistance is negligible?
(b) if skin resistance is negligible, what potential difference between the hands is needed for lethal shock current 100 mA? Your result shows that even small potential difference can produce dangerous curents when shin is damp.

Answer 1

Answer with Explanation:

We are given that

Resistivity,$\rho=5\Omega m$

Length of cylinder,l=1.6 m

Diameter ,$d=0.10 m$

Radius,$r=\frac{d}{2}=\frac{0.10}{2}=0.05 m$

a.Resistance,$R=\frac{\rho l}{A}$

$R=\frac{5\times 1.6}{\pi(0.05)^2}=1.02\times 10^3\Omega$

b.Current,I=100 mA=$100\times 10^{-3} A$

$1 mA=10^{-3} A$

Potential difference,V=IR

$V=100\times 10^{-3}\times 1.02\times 10^3=102 V$