Birds resting on high-voltage power lines are a common sight. the copper wire on which a bird stands is 1.28 cm in diameter and carries a current of 149

a. if the bird's feet are 4.12 cm apart, what is the potential difference across its body? copper's resistivity is 1.68 × 10−8 ω m . answer in units of µv.

Explanation:

First of all, let's find the cross-sectional area of the copper wire. The radius of the wire half the diameter:

So the area is

Now we can calculate the resistance of the piece of copper wire between the bird's feet, with the formula:

where

is the resistivity of copper

is the length of the piece of wire

is the cross-sectional area

Substituting, we find

And since we know the current in the wire, I=149 A, we can now find the potential difference across the body of the bird, by using Ohm's law: