if a tree is touching an electrical wire and we touch that same tree we don't get electrocuted?? why doesn't the tree light up.
2007-12-19 08:21:08 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Physics
I've seen them light up after a power-line touch.
Normally, they don't light up because wood, particularly if it is dry, is a good insulator. Not a GREAT insulator, mind you, but a decent one. But on a rainy day when the tree is wet and a wire touches a branch, you get a loud ZZZZAAAAPPPPP! and a cloud of smoke.
2007-12-19 08:35:03 · answer #1 · answered by The_Doc_Man 7 · 0⤊ 0⤋
SOmetimes trees do light up, if there is rain on a branch that touchs a powerline, it will conduct elecriticity and can cause a fire. If a tree is struck by lightning and you are under it, you can get shocked. Normally, wood is not a good electrical conductor so normally it is not a problem.
2007-12-19 08:26:17 · answer #2 · answered by Gary H 7 · 0⤊ 0⤋
Lots of variables.
Lets make a bad case.
Use the old voltage divider trick. A power line to ground is 13k/3^(1/2) ~7.5kV
Let's say you need a good 50v to shock you hand to foot (barefoot).
Let's say the tree is 5Mohm/m (sappy) and your body is 30kO (maybe your hand is a little sweaty).
x=length of tree from hand to line.
To get shocked
50 = 7.5K ((10M*30K)/(10M+30K)) / (5M*x + (10M*30K)/(10M+30K))
0.9 M assuming good contact with tree.
With 100kV line (the big ones) The line could be 12m from your hand and still give you a jolt.
POINT B, why doesn't it light up? Let's see how much power.
Best case 5Mohm/m Let's say 3 M.
(7.5k^2/15M)=power = 3.75W Thats less heat going to that tree than breathing on it would create. Nothing short of lightning will burn a tree unless some really strange circumstances were present.
2007-12-19 09:07:40 · answer #3 · answered by tyler497 3 · 1⤊ 0⤋
You could get electrocuted touching a tree that is in contact with a HV line if you happen to provide a better ground path than the tree.
It doesn't "light up" because its not a bulb.
2007-12-19 08:28:56 · answer #4 · answered by Poor one 6 · 1⤊ 0⤋
Dry wood is a poor conductor. But wet wood conducts electricity.
So it can be hit by lightening and get electrocuted.
2007-12-19 12:07:42 · answer #5 · answered by chanljkk 7 · 0⤊ 0⤋
because wood is a poor electric conductivity.
2007-12-19 08:34:24 · answer #6 · answered by jabba 3 · 0⤊ 0⤋
they do actually....you just dont see/feel it.
they have feelings, remember
2007-12-19 08:29:00 · answer #7 · answered by kay-g 2 · 0⤊ 0⤋