# Question

In a country setting it is common to see a hawk sitting on a single high-voltage electric power line searching for a roadkill meal (Fig. 17.19). To understand why this bird isn’t electrocuted, let’s do a ballpark estimate of the voltage between her feet. Assume dc conditions in a power line that is 1.0 km long, has a resistance of , and is at an electric potential of 250 kV above the other wire (the one the bird is not on), which is at ground or zero volts.

(a) If the wires are carrying energy at the rate of 100 MW, what is the current in them?

(b) Assuming the bird’s feet are 15 cm apart, what is the resistance of that segment of the hot wire?

(c) What is the voltage difference between the bird’s feet? Comment on the size of your answer and whether you think this might be dangerous.

(d) What is the voltage difference between her feet if she places one on the ground wire while continuing to hold onto the hot wire? Comment on the size of your answer and whether you think this might be dangerous.

(a) If the wires are carrying energy at the rate of 100 MW, what is the current in them?

(b) Assuming the bird’s feet are 15 cm apart, what is the resistance of that segment of the hot wire?

(c) What is the voltage difference between the bird’s feet? Comment on the size of your answer and whether you think this might be dangerous.

(d) What is the voltage difference between her feet if she places one on the ground wire while continuing to hold onto the hot wire? Comment on the size of your answer and whether you think this might be dangerous.

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