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Q & A: like a bird on a wire

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Most recent answer: 08/30/2009
Q:
We usually say that the birds sitting on the high tension wires dont get shocks bcoz the potential is same all along the wire and hence the bird doesn't get shock.But how can current flow when there is no potential difference.
- Prudhvi Raj Borra (age 16)
Machilipatnam,Andhra,India
A:
Good question. There really is a small potential change as you travel down the wire. That's needed to push current through the wire. just as you say. Since the wire is made of a rather thick piece of good metallic conductor, it takes only small potential differences to push large currents. The potential difference from one of the bird's feet over to the other is tiny.

The large potential differences are between the different wires, and between the wires and the ground. Anything touching two of the wires  or a wire and the ground will be electrocuted.

Mike W.

(published on 08/30/2009)

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