Birds resting on high-voltage power lines are a common sight. the copper wire on which a bird stands is 3.5 cm in diameter and carries a current of 32
a. the bird's feet are 2.1 cm apart. (b) calculate the potential difference across its body.

Explanation:

First of all, we need to calculate the resistance of the piece of copper wire between the bird's feet, which is given by

where:

is the resistivity of copper

is the length of the piece of wire between the bird's feet

is the cross-sectional area of the wire, with r being the radius. Since the radius is half the diameter:

the area is

And the resistance is

And given the current in the wire, I=32 A, we can calculate the potential difference across the bird's body by using Ohm's law:

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