Practice question · Multiple choice
A bird stands on a high-voltage line unharmed, and a person touching the same line would be killed. What is different?
Hints
- Ask what drives a current: voltage at a point, or a difference between two points?
- Both the bird's feet are on the same wire, centimetres apart. What is the potential difference?
Show the answer
C. Current needs a potential difference, and both feet are level
Why
Voltage at a point does nothing; a difference across you does. The bird's feet sit at nearly identical potential, so almost no current flows, while a person connects the line to earth and becomes the path. It is why linemen work from insulated buckets and why 'it is not the volts, it is the amps' is half-right at best.
Practise Electromagnetism
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