<_< newbie question: In chapter I on DC current talking about "shock current," the author explains that a bird perched on a high wire with two feet is not shocked beceause the bird is not across a load, hence no voltage. Later on, however, he talks about a downed power line and warns that to avoid shock you have to stand on one foot to prevent being shocked. This is a contradiction.

My own explanation is that in the bird instance the very small, "negligible" resistent offered by the stretch of wire is less than that of the bird body, so the current would go straight along the wire and not "take a detour" up one leg and down the other, thus "shocking" the bird, the bird body acting like a resister/load. In the second instance, the resistance offered by the ground/dirt is much greater than that offered by the human body, so the current in this case does indeed 'follow the path of least resistance" and goes up one leg, through the "human resister" and down the other leg completeing the circuit.

Is this right? Otherwise, what's the difference between two bird feet and two human feet?

Tony

 

Hi,

It's all in the conductor. The resistance of the wire the bird stands on has no measureable resistance over the distance between the bird's feet, so no potential difference will obtain. Therefore, no shock.

Plain old dirt is an indifferent conductor, though. Close to a downed power line, the difference in potential can be hundreds of volts per meter. If one stands in such a way that he bridges a high potential difference, then there is a severe shock hazard. The poorer the conductor, the greater the shock hazard.

 

Originally posted by beenthere@Nov 27 2004, 02:39 PM
Hi,

It's all in the conductor. The resistance of the wire the bird stands on has no measureable resistance over the distance between the bird's feet, so no potential difference will obtain. Therefore, no shock.

Plain old dirt is an indifferent conductor, though. Close to a downed power line, the difference in potential can be hundreds of volts per meter. If one stands in such a way that he bridges a high potential difference, then there is a severe shock hazard. The poorer the conductor, the greater the shock hazard.

[post=3827]Quoted post[/post]​

Thanks. That's what I figured. The contradiction in the text could throw off some neophytes...like myself!

Tony

 

hi friends,
i am new to this forum. And i have a doubt to ask you?
Is shock is because of current or voltage?