Question

You often see birds resting on power lines that carry currents of 50A. the copper wire on which the bird stands has a radius of 1.1cm. assuming the birds feet are 4.0 cm apart, calculate the potential difference across its body...


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V=IR
R=pL/A


I=50A
L=4.0cm
p=from table for copper
A=area of a circle using radius=1.1


then using these values solve for V...

im not sure if this is right..any guidance would be great..

Answer 1

That would just be the IR drop along the 4 cm of line. It is not going to be very large. Your method should lead to the right result.

The resisitivity of copper is 1.7*10^-6 ohm-cm. L/A = 4 cm/3.8 cm^2 = 1.05 cm^-1
R = 1.8*10^-6 ohms

Now do the IR.

There are also induced emf's in the bird's body due to the AC character of the current in the wire, but they are probably also small, and another story.