I saw a few youtube videos explaining that electricity doesn’t actually travel through wires but directly to the bulb from the battery. I understood their explanation. But now I have a doubt. Since energy flows directly to the bulb, can I shield the bulb in some way such that the circuit is complete and even then the bulb doesn’t light up?
In: Physics
No that’s not possible. A shield where a wire goes through isn’t a working shield against EM. Also I know the video you mean.
Right in the end there is a little hint about “wave resistance (impedance) of the wire”. The time until the “full” electricity reaches the bulb depends on the wire, just the first bit of energy is travelling through air, and you could indeed shield that to delay the light turning on by a few microseconds
Nope. Completing the circuit implies EM coupling, while shielding implies no coupling. Can’t have it both ways
You should watch the follow-up video by the same guy when he got called out for not really telling the truth in the explanation and resulting effects.
The speed at which the circuit knows its complete is different to the speed at which the energy moves to light up the lamp. The circuit checking happens at the speed of light in the dielectric, while electric charge (and thus power) happens at the speed of the conductor material…
The dielectric for most wires includes the insulation and air around it, while the conductor material (and thus power) has to go the actual length of the wire
I don’t understand the conclusion you’re presenting from the video, admittedly; electrons flowing through the bulb is what makes it light up. For an incandescent bulb, this is because this movement creates heat in the filament due to resistance to this flow, while an LED creates light by electrons jumping a band gap between the materials.
In direct current (DC), the electrons flow as a stream, unidirectionally travelling from one end of the battery to the other due to the voltage gradient/difference in charge. In alternating current (AC), there’s a cyclic shift of the direction of the electrons, meaning the electrons in the battery may never actually travel through the entire wire, but instead push and pull their neighbors through the entire system, which can be used to do work or still power things like lights.
Electricity is the flow of electrons in a direction. Electrons are negative and move towards positive charges. One atom passes it’s free electron to the next in a chain so to speak. Electricity does not flow if there is no circuit. That’s what a light switch does.
I believe the last thing you mentioned would be a dead short before the bulb in question made of a material with less resistance than the filament bulb or LED circuit. Electricity moves in the path of least resistance generally.
There’s …. A LOT to electricity. So, electricity does flow across wires to the load or draw in that the electrons are moving but the copper atoms themselves are not moving. I hope this makes sense.
I’m not sure what these said videos are imply, but wires (or some equivalent) are necessary to complete an electrical circuit. This can be proven by removing the wires and finding the load is no longer powered. A light switch works in the same way, making a circuit no longer complete.
Some energy goes direct to the wire near the bulb, since both wires are acting as antennae.
However, that’s just a tiny amount of energy. Most of the energy has to travel along the wire.
the electricity flows in the wire, but the actual energy travels throught the EM field.
But that field is there because of the moving electrons in the wire.
Its a little like the saying “Its not the fall that kills you, its the sudden stop when you hit the ground.” Technically correct, and useful in some contexts, but for the average person every day, its the fall that kills you.
Could you explain what you mean better? Electricity does in fact travel through the wires.
In D.C. (direct current) electrons are “pushed” out of the “push” side of the battery and flow through the copper wire hopping from copper atom to copper atom. They go into the bulb where some of their energy is used and some keeps going, then they return to the other side of the battery, the “pull” side where they collect. When all of the “extra” electrons from the push side of the battery have collected on the pull side of the battery the battery is used up and dead. Unless it is a rechargeable battery in which case the recharging moves all of the electrons back to the starting side.
If there isn’t a full circuit from the “pushing” side to the “pulling” side of the battery you get a traffic jam and no electrons move.
In A.C. (alternating current) there are two wires which is why you have two prongs on the AC plug. AC alternates pushing electrons down one wire and pulling from the other wire, then switching to pulling from the first wire and pushing from the other wire. This switch happens 60 times per second, back and forth.
Each time it pushes, for a brief moment 1/60 of a second, electrons are pushed into the copper wire and they push all of the electrons in front of them all the way to the pull side of the plug (all the way back to the power company’s transformer actually). Like dominos bumping each other the push goes all the way through. Then it switches and electrons are pushed back in the other direction. Since the same electrons are going back and forth it doesn’t collect up and run out like a battery.
Your light bulb only cares that electrons are moving through it, it doesn’t care if they are flowing through and out the other side, or if electrons are moving in one direction then in the other direction. Either way moving electrons gives it the energy it needs to work.
Ignore everything you read, electrons don’t move at all. The push energy from molecule to molecule like ping pong balls in a tube, and they only travel along the surface layer of the conductor.
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