Question

A bird lands on a bare copper wire carrying a current of 51

a. the wire is 8 gauge, which means that its cross-sectional area is 0.13 cm2. (a) find the difference in potential between the bird's feet, assuming they are separated by a distance of 5.1 cm.

Answer 1

The resistance of the piece of wire is

`R= (\rho L)/(A)`
where

`\rho = 1.68 \cdot 10^(-8)\Omega m` is the resistivity of the copper

`L=5.1 cm=0.051 m` is the length of the piece of wire

`A=0.13 cm^2 = 0.13 \cdot 10^(-4) m^2` is the cross sectional area of the wire
By substituting these values, we find the value of R:

`R= (\rho L)/(A)=6.6 \cdot 10^(-5) \Omega`

Then, by using Ohm's law, we find the potential difference between the two points of the wire:

`V=IR=(51 A)(6.6 \cdot 10^(-5) \Omega )=3.4 \cdot 10^(-3) V`