So as we know for a person to get electrocuted a circuit needs to be completed. You cannot stand on a wooden chair and get electrocuted. So when you stand on a wooden chair and touch a live wire, how does the electricity figure out that you’re standing on an insulator? Does the electricity pass through you first before failing to complete the circuit because of the wood?
In: 19
It is actually very closely related to the similar question “if I poke a stick against a wall, how does my end know that the stick stopped?”.
Both happen because the electrons are first told to move in that direction, but soon bump into each other in a kind of traffic congestion. This actually does not happen instantaneously without any effect, in both settings there is actually a small wave of slightly more electrons/atoms that travels until it hits the stopping point (and then travels backwards):
When compared with cars, you are at the end of the traffic jam, each car leaving 1 meter to the next one. Now you close your gap. The guy before you does not like you being that close and thus moves forward a bit. Then the next one does, too, and so on. The guy at the very front however cannot move forward, and as soon as the guy behind him realizes it, they move backwards again, and so on.
However, the speed is very different between both situations: it travels with a significant fraction of the speed of light for electricity, and with the speed of sound (in the respective material) for the stick. Part of that reason is that the latter has those entire bulky atoms move, while conductivity is a bunch of tiny electrons speeding around.
It doesn’t know anything.
You get electrocuted as electrons flow through you to get from point A to point B.
This means there needs to be two things:
1) A reason to move (electric field) which is created by the live wire.
2) Electrons capable of moving. And this is where insulators come in. Materials aren’t actually conductors **or** insulators, they’re on a range somewhere in between. Insulators are materials that strongly hold onto the electrons they have, so it takes a very big field (a good reason) for the electrons to move. In a conductor, the electrons are easily seperated, and motivated to move.
So when you are on a chair, the electrons from the chair and ground are being pulled (or pushed) by the electric field, and not budging. So nothing happens.
If you stand on a conducting surface, the electrons readily jump free and race through your body, which is generally a bad thing as they rip apart thing they slam into on the way (heat)
You can absolutely stand on a wooden chair and get electrocuted.
Electricity moves from a place where electrons are bunched up to an area where they can spread out — like gas helium in a canister moving into a balloon.
You can put barriers in the way, like a valve, but if you cram enough potential into one place, it will explode out (helium blowing up the gas canister because of too much pressure, or voltage arcing or piercing an insulating material to move to somewhere else).
Electrocution refers to being killed by electrical current. It doesn’t take much to stop a person’s heart, and the current doesn’t need to go to ground — it only needs to pass through the heart, which it can if a person completes a circuit with their two hands (in one arm and out the other). Mind you, it’s possible to head or hand to floor too, if the conditions are right.
There are materials that have a nice atomic structure that lets electrons flow easily through it like water through a pipe. There are also things that have a structure that doesn’t let electricity pass through easily, like water through concrete. When something restricts the flow, that’s called resistance. If the resistance is high, the flow is stopped (at least until the force is enough to overcome it). Ever see a spark travel from one thing to another (your finger to a doorknob after scuffing your feet on the carpet, perhaps)? That’s electricity overcoming the resistance of air to leap across the gap — about 75,000 volts are required to jump a 1” air gap.
Electricity doesn’t know where to go anymore than water does. It simply flows “downhill”, which really means “from a spot where electrons are bunched together trying to push each other away, to a place where they are spread out as much as possible or are fully absorbed by something”. It doesn’t figure out that you are standing on an insulator, it simply bumps up against too much resistance to move.
It doesn’t.
A high voltage wire is in a higher “state”, than everything around it. Imagine the wire like an oxygen tank. The high voltage means the electrons, like the air, is under high pressure. It wants to go anywhere there’s low pressure/voltage. *
Air in the oxygen tank wants to get out everywhere. But the tanks walls don’t let the air out. If you open the valve, there’s only one way out, the valve. The air doesn’t “figure out” where the valve is, but it’s the only way out.
Same with insulators/conductors. Electricity will try to make any path to close the loop. The conductor is the easiest path, so most of the electricity will flow that way.
Note that I said most, not all. No insulator is perfect. Any insulator will leak small amounts of electricity. Furthermore, insulators can catastrophically break down. This is called dielectric breakdown, and when you see electric arcs or lightning bolts, this is what’s happening. The voltage is so high, and the electric fields are so strong, air will ionize and turn into a conductor. This would be the oxygen tank exploding.
*This isn’t a perfect analogy as in electrical systems the loop needs to close. If you touch the high voltage end of a battery, you’ll get energized to a high voltage state, but because there’s not electrical path back to the negative terminal, no current will flow. But in your high voltage state, it’s really easy to get an unforeseen leakage path, so don’t do this at home.
Latest Answers