Eli5 How does electric current notice if there is a “connection” e. g. to the ground?



Maybe not the best title to explain what I mean, English is not my first language.

I just saw pigeons in a train station, sitting on electric wires. Obviously it does not die since it does not have contact to the ground or anything else that could transmit the electricity.

But how does the electric current notice if there is a way through the pigeon (or anything else) or not? Since the pigeon is alive, the current apparently does not flow through it?

So how does the current know?

Yes, I’m not the best in physics lol

In: Physics

Current flows the oposite direction to electrons and Current flows from positive to negative and electron flows from negative to positive so if you ground something the electrons flow up from it.
Both try to find the path of least resistance and the more electrons has or the looser the electrons are packed the easier for them to flow.

The same way water knows there’s a hole in a bucket. If that wire wasn’t insulated anything that conducts will get shocked no matter what side of the wire it’s on.

The same way water “knows” there’s a hole in a bucket.

Electricity “flows” towards areas of lower potential, lower charge density. Electrons can technically go through anything – air, pigeons, rubber – just like how water flows down hill but will “rise” if there’s enough pressure/flow entering an area with insufficient outlet.

With electricity, you can sort of view highly conductive things as “downhill” and less conductivity things as “uphill.” The physics of electron flow determines that electrons flow “downhill,” but they can technically flow “uphill” under the right conditions.

Same way that water “knows” when there is a leak in the container that is holding it. Just as the force of gravity pulls the water through the leaky container to the ground, the electromagnetic force pulls electrons from their container to their ground.

Electromagnetic field is everywhere, it is continious and any changes propagate at the speed of light. Electrical curent flows from high to low potential in this field. Some materials materials facilitate this flow really well, like metal wires, while others strongly empede the flow, like air. While there theoreticaly is current from the wire, to the bird, to the ground it is increadibly small, the bird doesnt even notice it.

There’s no noticing. Electrons don’t have a brain. They flow in every material whether it has current flowing through it or not. Just that if you apply potential across a material with loosely bound electrons, they might still move in different directions, but there is a net flow in direction opposite to the potential.

Now, let’s say the wire isn’t insulated, and the pigeon comes and sits on it. Since both it’s legs are in contact with the wire, it provides a straight path for electrons to flow through, with potential difference across it’s legs due to the wire. Then, he is bound to feel the shock. Now let’s say the pigeon sits with one leg on the wire and another in the air like a yogi. Then, the electrons will still flow through one leg to its body, but since these electrons have nowhere to go, and nothing is there to suck off the electrons off his body (which is what a battery does), this will not persist. The electrons will flow from one leg and evenly distribute on his body until his body’s electric potential becomes same as that of the leg, which will happen pretty fast, after that there won’t be a net flow. Current is sustained flow of electrons, and since here the flow started and finished almost instantly, he won’t feel anything.

TLDR: Current doesnt know what lies on the opposite side of a wire or a material, the elctrons flow nonetheless. It’s just that to sustain a net flow of electrons, you need a source and a sink, across which is maintained a potential difference, and you need a medium which allows the electrons to move.

Edit: What’s the downvote for? This is not something you can have opinions about, these are facts. Idiots.

Charged particles become “aware” of their surroundings by spontaneously emitting and absorbing photons (as a result of fluctuations allowed by quantum mechanics). Photons are just light. Thus an electron “decides” on its best path by emitting and recieving light, which moves so much faster than the current that it seems instantaneous.

There is a whole different discussion on why the wire is a better path than through the bird and then the air, but I don’t think that’s what you’re asking for.