There are certain moments in life I wish I had actually listened to the teachers at class instead of dreaming about the knight in shiny armour.
The knight never came ( must be stuck in a traffic jam??)and I am in the process of becoming an idiot, at least in front of my children.
All I was trying to do was to explain why the birds sitting on a transmission line don’t get zapped.
Technically it is simple, there is no circuit unless the poor bird touched the earth wire.
I explained the way current moves from high to low and the fact that both feet of the bird touches the wire makes it possible for the current to bypass the bird’s body!
But then my child wants to know why there is no electricity going through the bird, since its body is a conduit for electricity.( otherwise it won’t get zapped!)
I know it has something to do with the birds body being at the same voltage as the wire..What I don’t know is, why it is so..and before I get fried, help me.
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http://www.fas.harvard.edu/
~scdiroff/lds/
ElectricityMagnetism/BirdonaWire
/BirdonaWire.html
Its simple ..potential difference is the thing that causes current flow. Explain like this. If both feet are on the roof of a building its fine or both feet are on the bottom of the building. Only if one tries to touch both the roof and the bottom (mechanical equivalent of potential difference) then one falls (or gets a shock)
Lekha: ” Although the bird on the wire would also be at this voltage, there is no part of its body that isn’t” This is the part we are stuck at.. How does the bird be on the same voltage as the wire?
Disp_mallu: No luck..
She understands the potential difference..what she wants to know is how the bird manages to be at the same voltage as the powerline so as not to have current passing through its body while it is on the transmission line.. She also wants to know if there is a power fluctuation, will the bird gets toasted?
Hi Sarah,
Here’s what I remember from school:
1) When the bird lands (with both feet) on the wire, its body gets charged. This is how it acquires the same voltage as the wire.
2)While the body is a conduit for electricity, it is a far poorer conductor than the copper wires in the electrical lines. There’s no reason for electricity to travel through the body when a better conductor is present.
3) Nothing should happen if the power changes as the body is still a poor conductor relative to the wire. Power fluctuation is a fairly common phenomenon. Even if the power is down, nothing should happen (in the light bulb experiment, it is absurd that the light bulb would light up when the current stops flowing)
Here is a fun video for the kids:
http://www.youtube.com/watch?v=1288Ri5Ns8g
pooh: You have no idea how much you have helped me. Thank you.